Tokyo has reported the highest number of new Covid-19 cases in almost six months, with the Olympics due to open in the capital in just nine days, reports Reuters.

The city government has said there were 1,149 new cases, the highest daily tally since January 22, adding to evidence that a new fifth wave of infections is under way, driven by more infectious virus variants and a low vaccination rate.

Amid rising cases, the government declared a renewed state of emergency for Tokyo and surrounding prefectures last week and Olympics organisers announced that no fans would be allowed at events in those areas.

"Once it's on an increasing trend, it's too late," said Haruka Sakamoto, a physician and researcher at Keio University in Tokyo. "Probably the number of newly infected cases will continue to increase for few more days."