The head of the WHO has said that the time to act against the coronavirus was “actually more than a month ago,” while urging countries not to squander a second opportunity to stem the disease.

Tedros Adhanom Ghebreyesus, WHO director-general, told reporters that certain countries had not marshalled their resources quickly enough.

He said: "We have been saying to the world that the window of opportunity is narrowing and the time to act was actually more than a month ago, two months ago.”

"But we still believe that there is opportunity. I think we squandered the first window of opportunity. This is a second opportunity which we should not squander and do everything to suppress and control this virus,” he added.

The WHO chief is to join a summit of G20 leaders on Thursday to discuss the outbreak and to raise issues such as funding.

On Wednesday, the WHO also said that countries that had enforced lockdowns needed to identify new cases and to do all they could “to suppress and control” the virus.

The world's biggest lockdown began in India at midnight on Tuesday local time.

Its 1.3 billion citizens have been asked by President Narendra Modi to comply with the restrictions for a minimum of 21 days.