RIGA, Latvia — Russian authorities are forcing Ukrainians who seek safety to submit to strip searches and interrogations, placing some refugees in guarded camps, stripping them of their vital documents and in some cases forcing them to remain in Russia, according to displaced Ukrainians, volunteers helping refugees, and Ukrainian and Western officials.

At least 1 million Ukrainian civilians have fled the fighting into Russia, according to Russian Defense Ministry numbers that the Ukrainian government also accepts as valid. In many cases, especially in the devastated city of Mariupol, many residents were effectively forced into Russia with no option to seek refuge on friendlier soil. In other cases, especially in the breakaway territories of eastern Ukraine, the travel to Russia was voluntary.

Almost everyone has had to pass through “filtration camps,” a perilous process in which Ukrainians are strip-searched and interrogated. People suspected of having sympathies to the Ukrainian military are being detained and tortured, according to refugees, representatives of volunteer organizations, and Ukrainian and U.S. officials.

“They are disappearing people who talk openly about pro-Ukrainian positions,” said Lyudmila Denisova, the Ukrainian parliament’s human rights ombudsman.

Not every story has ended badly. In some cases, Ukrainians who wanted to pass through Russia and go to another country were able to do so, even if they were staunchly pro-Kyiv. Some spoke appreciatively of help from local Russian humanitarian groups.

But many Ukrainians have been transferred to a constellation of temporary refugee settlements across Russia’s vast territory, leaving them trapped inside the country that had targeted them with hatred and leveled their homes.

At the camps, the questioning often continues, refugees said.

“’Who are you for?’ they asked. ‘For Russia or for Ukraine?’” said Bohdan, a 26-year-old construction worker from Mariupol, who escaped the city with his wife and 7-year-old daughter in mid-March when buildings in their neighborhood began collapsing because of heavy fighting. He spoke on the condition that his family name not be published because he fears for his security.

He fled into Russian-held territory, the only place he could reach at the time. Eventually, he made his way to a refugee center in Yalta, in Crimea, on the site of an abandoned Soviet health resort that he said had not been renovated since then. He was repeatedly interrogated about his loyalties.

“I said, ‘You are interesting people. There was a war happening in my homeland, Russian soldiers attacked, and my house was smashed. And you want me to shout pro-Russian proclamations?’” he recalled telling them.

Russian officials also questioned him about the location of Ukrainian military positions inside Mariupol, he said.

He and his family went on to leave Russia in mid-April with the help of some foreign volunteer organizations, he said, and are now in Stockholm. The rest of his group of refugees was taken to a run-down health resort somewhere in a remote area of Russia, more than 600 miles inside the border, he said.

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Alexander Shevchuk, 19, who studied information technology at a local college, had lived with his family on the eastern bank of the Kalmius River that bisects Mariupol, close to the headquarters of the pro-Kyiv Azov Regiment that has been a target of Russian firepower.

From the ninth floor of a nearby apartment building, he could witness the city’s methodical destruction by Russian artillery. “For the first time, I understood what apocalypse looked like,” he said. When he was caught in the crossfire inside a shuttered supermarket while hunting for food, a fragment of an artillery shell lodged in his back, he said. Many others around him were killed.

When soldiers from the breakaway Donetsk People’s Republic captured the area where Shevchuk’s family was hiding at the end of March, there was little option but to try to make it to Russia. Even before he reached the border, he said, he endured repeated rounds of questioning by separatist soldiers, Russian border guards and agents of Russia’s FSB, the internal security agency; they all tried to establish whether he had taken part in fighting. He was strip-searched repeatedly and checked for pro-Ukrainian tattoos and the calluses and bruises that can be signs of having handled weaponry.

Shevchuk said he was questioned about his long hair and goatee, which soldiers and border agents believed was a sign of Ukrainian nationalism. Men who had military certificates that suggested they had actively served in the Ukrainian army were taken into custody, he said. One acquaintance of his was taken to another building, then beaten, tortured and robbed before he was released again.

“I was terribly afraid,” Shevchuk said. “I was scared they would say I was from Azov,” the pro-Kyiv battalion, he said.

Shevchuk and his family ultimately spent about a week at a “filtration camp” on the Ukrainian side of the border, awaiting a final round of questioning. The refugees were given questionnaires asking their attitudes about the Ukrainian military, the Ukrainian government and various elements of Ukrainian life. Shevchuk and the others wrote “negative,” since they figured that was the correct response. “We didn’t want any problems,” he said.

Interrogators also checked phones and tablets, looking at apps and photos to try to find any trace of military combat, and removed SIM cards from some of them because, they said, they could be used for targeting by the Ukrainian military.

If any of the Ukrainians slipped up and referred to what had happened as “war,” the interrogators would immediately become aggressive, Shevchuk said. “Why do you think this is war? War against whom?” he said they asked. “You know you shouldn’t say this word.”

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Many refugees are careful about expressing their views openly on Russian soil, unsure about the loyalties of other displaced Ukrainians around them and of the Russians who are helping them.

“They will never say anything against Russia, because they don’t trust us,” said Laila Rogozina, head of the reception office at the Civic Assistance Committee, a Russian volunteer organization that helps refugees and has been harassed by the Kremlin.

The treatment of refugees inside Russia appears to vary widely. Much depends on luck. Some border guards prevent Ukrainians without the proper documents from leaving Russia. Others are laxer, according to Ukrainians who have made the passage.

“It’s like roulette. They can let you out or send you back” at the border, said Kirill Zhivoy, a coordinator at Volunteers in Tbilisi, a group in the capital of Georgia that is helping Ukrainians who manage to cross the border from Russia.

Some refugees are able to find decent short-term housing. Others have access only to guarded camps where refugees cannot come and go as they please.

Ukraine’s Western backers have expressed alarm.

“If women and children and elderly and other individuals are being displaced forcibly,” Michael Carpenter, the U.S. ambassador to the Organization for Security and Cooperation in Europe, told reporters last week, “that would be a war crime and it would just be appalling as a completely uncivilized endeavor.”

The Russian Foreign Ministry has said the reports of forcible displacement are “lies.”

“We are talking about checkpoints for civilians leaving the zone of active hostilities,” the Russian Embassy in Washington wrote in a Telegram post. “In order to avoid sabotage operations by Ukrainian national battalions, soldiers of the Russian armed forces thoroughly inspect vehicles heading to safe regions. We will detain all bandits and fascists. The Russian military does not create any obstacles for the civilian population, but helps them stay alive and provides them with food and medicines.”

Many Ukrainians arrive in Russia with little more than the clothes on their backs, leaving them few choices. Some lack money for bus tickets or understand the country’s labyrinthine bureaucracy. Others are unfamiliar with Russia’s vast geography, and do not appear to understand that promises of extra support and temporary housing in Russia’s eastern regions can take them thousands of miles away from Ukraine.

“Some people from Mariupol said they’d already decided to go to the Khabarovsk region” on Russia’s far eastern Pacific coast, a six-day train journey from Moscow, said Danil Makhnitsky, the head of a Moscow-based volunteer organization, Society.Future, which is helping refugees with supplies and practical support. Some of the refugees don’t understand where they are going when they sign up, he said.

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If Ukrainians want assistance from the Russian government — often a necessity, since Ukrainian cash can’t be exchanged into Russian rubles — they often need to give up their passports to get it. Both temporary housing and asylum require turning over documents to the authorities. It can be difficult to get them back.

“They are taking Ukrainians hostage,” said Denisova, the Ukrainian human rights ombudsman.

Even Ukrainians who say that Russia was their preferred destination say they worry about the challenges of being a refugee there.

“The migration service said that if I want my passport back, I will need to write an official letter saying that I am refusing this temporary residence asylum certificate,” said Marina Tsymbalova, 33, a refugee from Mariupol who is in Moscow with two of her daughters and has applied for a one-year temporary asylum status in Russia that required her to hand over her Ukrainian documents.

“I want to go back at some point,” she said. “My mom is there, and my older daughter. I worry about them.”

Once Shevchuk and his family had reached the Russian side of the border, they spent about a week in temporary housing for refugees before buying bus tickets to neighboring Georgia. He said they had been able to move around freely and had wanted to leave as quickly as possible. It was oppressive to stay in a country where most people support the war and billboards everywhere are plastered with the letter Z, which has become a symbol of the invasion. Inside Russia, it was not possible to express his views openly, he said.

“We had a peaceful life. They took it away from me and left me with nothing,” he said. “All of a sudden they tell you you’re being saved. Saved from what? I’ve never seen fascists or Nazis.”