GENEVA — The World Health Organization on Wednesday called for $675 million (613 million euros) in donations for a plan to fight the novel coronavirus, mainly through investment in countries considered particularly "at risk".

"Today we're launching a strategic preparedness and response plan.... We're requesting $675 million to fund the plan for the next three months," WHO chief Tedros Adhanom Ghebreyesus said at a news conference in Geneva.

"Our message to the international community is invest today or pay more later," Tedros said, adding that the funding appeal was "much less than the bill we will have to pay if we do not invest in preparedness now".

Tedros said $60 million of the funds would be for WHO operations while the remainder would go to countries requiring assistance to guard against the deadly virus.

He said WHO was sending 500,000 masks and 40,000 respirators to 24 countries from its warehouses in Dubai and Accra.

Tedros also hailed a $100 million donation from the Bill and Melinda Gates Foundation announced earlier on Wednesday for virus testing, treatment and vaccine research.

Asked about Britain's call for its nationals to leave China, Tedros said: "That blanket approach may not help. We encourage all countries to make decisions based on evidence."

He said an international expert mission being organised by WHO would be leaving for China "very, very soon".

The Bill & Melinda Gates Foundation pledged Wednesday to commit up to $100 million for the global response to the novel coronavirus epidemic that has claimed nearly 500 lives.

The funding will be used to strengthen detection, isolation and treatment efforts, the foundation said, including protecting at-risk populations and developing vaccines and diagnostics.

"Multilateral organizations, national governments, the private sector and philanthropies must work together to slow the pace of the outbreak, help countries protect their most vulnerable citizens and accelerate the development of the tools to bring this epidemic under control," said Gates Foundation CEO Mark Suzman.

The amount includes $10 million previously pledged in late January.

The foundation said it would direct $20 million to organizations like the World Health Organization, the US Centers for Disease Control and Protection, the National Health Commission of China and the Chinese Center for Disease Control and Prevention.

A further $20 million would be allocated to help public health authorities in sub-Saharan Africa and South Asia, regions which have been disproportionately affected by recent epidemics like the H1N1 (swine flu) pandemic of 2009.

The foundation also pledged up to $60 million to accelerate the discovery, development and testing of vaccines, treatments and diagnostics for the virus.

The tiny central African state of Equatorial Guinea said Wednesday it would give $2 million (1.8 million euros) to China to help it tackle Coronavirus.

The government, which has developed close ties with Beijing, said the donation was a mark of "support and solidarity."

Authorities in China warned Wednesday they faced a severe shortage of hospital beds and equipment needed to treat a growing number of patients stricken by the new coronavirus, as cities far from the epicentre tightened their defences.

Central Hubei province reported 3,156 new infections, its biggest single-day jump in the outbreak that has spiraled into a global health emergency with cases reported in over 20 countries.

Among those new cases was a newborn, who was diagnosed just 30 hours after being born.

Despite authorities building a hospital from scratch and converting public buildings to accommodate thousands of extra patients, there was still a "severe" lack of beds, said Hu Lishan, an official in Wuhan, the quarantined city where the virus first appeared -- and where doctors are now overwhelmed with cases.

There was also a shortage of "equipment and materials," he told reporters, adding that officials were looking to convert other hotels and schools in the city into treatment centres.

As the number of confirmed infections nationwide exceeded 24,000, a growing number of cities have imposed a range of restrictions far from Hubei, as authorities battle to contain the virus that has killed nearly 500 people.

Millions of people, from the eastern industrial heartlands to near the northern border with Russia, have been ordered to stay indoors as authorities battle to curb the outbreak.

New cases emerged abroad, with 10 people testing positive for the virus on a cruise ship quarantined off the coast of Japan with thousands on board.

Italy announced that passengers from every international flight would be scanned for fevers, while Vietnam, which has detected 10 cases, joined a growing list of countries banning arrivals from China.

And Hong Kong, which reported its first coronavirus death this week, said anyone arriving from the mainland will face a mandatory two-week quarantine from Saturday.