Covid 19 coronavirus: Three dead as Tokyo cases explode

Police patrol outside the Ibaraki Kashima Stadium prior a men's quarterfinal soccer match between Japan and New Zealand. Photo / AP

The cases of Covid in Tokyo have exploded with 4058 testing positive today, along with three deaths.

It's a frightening development for the city with the new cases reaching all-time record highs during the Olympics.

The World Health Organisation said on Friday that Japan was doing its best to minimise the risk of Covid-19 spreading during the Tokyo Olympics but stressed there was no such thing as zero risk.

Local residents receive their first dose of the Moderna Covid-19 vaccine shot in Tokyo. Photo / AP

The World Health Organisation's warning came as Japan extended a virus state of emergency in Tokyo and expanded the measure to four more regions as it battles a record surge in infections a week into the pandemic-postponed Games.

"There is no zero risk. There could be less or more risk. And then, for things to happen with low risk, you try your best," WHO chief Tedros Adhanom Ghebreyesus said.

Japan and the International Olympic Committee (IOC) "did their best to minimise risk, because nobody should expect zero risk", he said.

"I know that they have done their best, and we have supported them all along."

Across Japan, new virus cases topped 10,000 for the first time on Thursday, and a string of government officials and health experts have warned that the more contagious Delta variant is fuelling a dangerous surge.