A Chinese doctor, among the first to raise the alert about China's new coronavirus, himself died from the virus on Friday, showing the depth of a worsening crisis that has killed at least 630 people.

Global panic also spread, with thousands trapped on quarantined cruise ships.

Ophthalmologist Li Wenliang died at 2.58am (1.58am Thai time), Wuhan Central Hospital said in a post on its verified account on Chinese social media platform Weibo.

The 34-year-old sent out a message about the new coronavirus to colleagues on Dec 30, but was later among eight whistleblowers summoned by police for "rumour-mongering."

He later contracted the disease while treating a patient and has been hailed as a hero by Chinese internet users.

Li was among more than 28,000 people who have been infected in China, where authorities are struggling to contain the outbreak, despite ordering millions indoors in a growing number of cities.

The number of confirmed deaths in China from the new-coronavirus outbreak rose on Friday to at least 630 after hard-hit Hubei province reported 69 new fatalities.

In its daily update, Hubei's health commission also confirmed another 2,447 new cases in the province, where the epidemic began.

Thousands of holidaymakers on cruise ships in Hong Kong and Japan face an agonising wait to find out if more among them have been infected.

At least 20 people on the Diamond Princess -- off Yokohama since Monday -- have tested positive. Some 3,700 passengers and crew from more than 50 countries have been confined to quarters.

Japanese Prime Minister Shinzo Abe said another cruise ship, the Westerdam, was heading to the country with one confirmed case.

He said no foreigners from the ship, capable of carrying nearly 3,000 passengers and crew, would be allowed to disembark.

In Hong Kong, 3,600 people spent a second night confined aboard the World Dream. Authorities conducted health checks after eight former passengers tested positive for the virus.

One person has died after contracting the virus in Hong Kong.

After Britain advised nationals to leave China, Beijing's ambassador to London said there should not be "such a panic."