FILE PHOTO: Tokyo governor Yuriko Koike speaks at the opening ceremony of the Ariake Arena, which will host volleyball and wheelchair basketball competitions in Tokyo 2020 Olympic Games in Tokyo, Japan February 2, 2020. REUTERS/Kim Kyung-Hoon

TOKYO (Reuters) - The governor of the Japanese capital warned on Monday that a lockdown of the city was possible if it saw an explosive rise in coronavirus cases, and called on event organizers and residents to exercise restraint to avoid such a drastic step.

Governor Yuriko Koike said the next three weeks were critical for whether Tokyo would see an “overshoot” - an explosive rise - in virus cases.

“It is possible that depending on developments, we may need to take strong measures such as a so-called lockdown of the city,” Koike told a news conference.

“We must, in any case, avoid that. Therefore, I want to ask all of the people of Tokyo for your further cooperation.”

Warning that the virus could spread from young people to the elderly and others at risk of serious illness, she urged all residents to have a shared sense of crisis.

Koike said she agreed with Prime Minister Shinzo Abe that the postponement of the Olympic Games, due to open in Tokyo on July 24, would not be ruled out but added that their cancellation was unthinkable.

Tokyo has had 138 coronavirus cases including four deaths as of late Sunday. At the current rate of spread, the number is expected grow by 530 through April 8, according to experts advising the city.