The death toll from the coronavirus outbreak in China has reached 1,380.

The National Health Commission said there were 121 deaths on Thursday from the strain of coronavirus, officially named Covid-19 by the World Health Organisation, as the number of new cases jumped by 5,090 to 63,581.

The number of reported cases has been rising more quickly after the hardest-hit province changed its method of counting them Thursday.

Hubei province is now including cases based on a doctor’s diagnosis and before they have been confirmed by laboratory tests.

China’s health commission said the change in counting methodology was aimed at identifying suspected cases in which the patient has pneumonia so they can be treated more quickly and reduce the likelihood of more serious illness or death.

It was also seen as a reflection of a chaotic crush of people seeking treatment and the struggle to keep up with a backlog of untested samples.

Hong Kong China Outbreak
Flower shop owner Iris Leung delivered face masks along with flowers on Valentine’s Day in Hong Kong (Vincent Yu/AP)

“Clearly in Wuhan, the health system is under extreme pressure and so the first priority has to be the patient,” said Mark Woolhouse, a professor of infectious disease epidemiology at the University of Edinburgh.

Elsewhere, Japan confirmed another case, a Japanese man in his 70s, a day after it reported its first death from the virus.

Japan now has 252 confirmed cases, including 218 from a cruise ship that has been quarantined in Yokohama.

Covid-19: confirmed cases
(PA Graphics)

More than 560 cases have been confirmed outside mainland China and there have been three deaths, one each in the Philippines, Hong Kong and Japan.

In an unprecedented attempt to contain the disease, the Chinese government has placed the hardest-hit cities — home to more than 60 million — under lockdown.

People are restricted from entering or leaving the cities, and in many places can only leave their homes or residential complexes for shopping and other daily needs.