The death toll from China's new coronavirus outbreak has risen to 259 and the tally of confirmed infections has surged to nearly 12,000, the government said on Saturday.

The National Health Commission said in its daily update that 46 more people had succumbed to the respiratory disease.

All but one of the new deaths came in hardest-hit Hubei province, the epicentre of an outbreak that has spread around the world.

The virus emerged in December in Hubei's provincial capital Wuhan, and has been traced to a meat market that sold wild game.

The number of infections in China also rose, by 2,102, bringing the nationwide total to 11,791.

That's despite unprecedented quarantine measures imposed last week on millions of people in Hubei and aggressive preventive steps elsewhere in the country.

The number of new deaths and newly confirmed cases have both spiralled higher on a daily basis since China sounded the nationwide alarm a week ago.

The epidemic has spread far and wide as huge numbers of Chinese travelled within and outside the country for the Lunar New Year holiday that started last week.

It has since ballooned into a global health emergency with cases in more than two dozen countries.

The top Communist Party official in Wuhan expressed "remorse" on Friday, saying local authorities acted too slowly in containing the virus.