Japanese Prime Minister Yoshihide Suga said the government must be on high alert as virus cases begin to rise in the capital, about three weeks before Tokyo hosts the Olympics.

“While there is a downward trend across the country as a whole, there is a slight upward trend in the capital region,” Suga told reporters Monday. “We must be on a high state of alert in dealing with the virus.” He added that he would be nimble in adjusting policies to deal with the situation.

Case numbers in Tokyo have been creeping up over the past week, since Suga lifted a state of emergency imposed to rein in infections. Any sharp increase could mean the emergency is reintroduced, further restricting residents’ activities even while the games are taking place.

The seven-day moving average of new virus infections recorded in Tokyo rose to 477 on Sunday, compared with 388 the previous week.

Suga’s comments came as the capital’s government announced Tokyo Governor Yuriko Koike would take a few more days away from public duties on the advice of a doctor, extending an already week-long absence.

Koike had been expected to return to work Monday, after taking time off to recuperate from fatigue. She was taken to a hospital last Tuesday, Kyodo News reported, without saying whether she had received a specific diagnosis.

Koike, 68, has led Tokyo’s response throughout the coronavirus crisis, often appearing to adopt a more cautious stance than Suga’s government. She has retained relatively strong public backing, with 57% of respondents to a poll of Tokyo residents published by the Asahi newspaper on Monday saying they supported her.

Koike said on June 7 she had received her first dose of a coronavirus vaccine.

The political veteran has stepped out of the spotlight at a critical time, just before local elections in Tokyo on July 4. Koike’s term as governor has three more years to run, but she must work closely with the victorious parties in the assembly, which may include Suga’s Liberal Democratic Party.

Controversy continues to rage over the Olympics, which are set to open July 23. About 58% of respondents to a Mainichi newspaper survey published on Monday said they opposed the games. Japan’s Imperial Household Agency even weighed in, saying last week Emperor Naruhito may have concerns the Olympics could cause coronavirus infections to rise.

About 55% of respondents to the Asahi survey said they approved of Koike’s handling of the virus, compared with 35% who said they didn’t. Asked about her handling of the Olympics, voters were evenly divided, with 42% saying they approved and the same percentage disapproving.

Koike, a former TV news anchor, defense and environment minister, left her seat as a Liberal Democratic Party member of parliament in her successful bid to become the first female governor of Tokyo in 2016. Her party challenged then-Prime Minister Shinzo Abe’s LDP unsuccessfully in parliamentary elections the following year.