Hospitals in Japan's second largest city of Osaka are buckling under a huge wave of new coronavirus infections, running out of beds and ventilators as exhausted doctors warn of a “system collapse”, and advise against holding the Olympics this summer.

Japan's western region home to nine million people is suffering the brunt of the fourth wave of the pandemic, accounting for a third of the nation's death toll in May, although it constitutes just seven per cent of its population, Reuters reports.

The speed at which Osaka's healthcare system was overwhelmed underscores the challenges of hosting a major global sports event in two months' time, particularly as only about half of Japan's medical staff have completed inoculations.

“Simply put, this is a collapse of the medical system,” said Yuji Tohda, the director of Kindai University Hospital in Osaka.