While Hong Kong leader Carrie Lam has ordered the suspension of the high-speed rail service between the city and mainland China from midnight on Thursday and all cross-border ferry services, the unions said it was not enough.

"Front-line colleagues are in a panic as they are exposed to high risk of getting the virus while at work," said Railway Power, which represents about 500 workers from metro operator MTR Corp.

The Hospital Authority Employees Alliance (HAEA) said it welcomed the steps the government had taken but wanted it to close the entire border and would meet on Saturday to discuss what more action it could take.

"There is still a considerable distance from our goal of full-scale preventive measures of infection control," the union said in a statement.

Chris Cheung, treasurer of the HAEA, which has more than 18,000 members, said many of them planned to begin phased strike action next week unless their demands were met.

The former British colony has confirmed 10 cases of the coronavirus, with one person in critical condition. The epicentre of the outbreak is the central Chinese city of Wuhan, where it is believed to have jumped to humans from an animal in an illegal wildlife market.

The health scare comes after months of at times violent anti-government protests in Hong Kong sparked by fears its autonomy, guaranteed under a "one country, two systems" formula, is being eroded by Beijing.

Protesters frustrated by the city government's refusal to make concessions on demands for full democracy have in recent months formed about 40 unions as a way to press their campaign and at least a dozen of them have come out in support of the HAEA's proposed strike.

Lam has said it is "inappropriate and impractical" to close the entire border.

The threat of strike action comes as Hong Kong residents have been scouring shops for face masks and joining long queues as supplies dwindle.

Berry So, a waiter, said he had queued up from 2 a.m. outside one shop.

"I've been waiting six to seven hours," said So, who failed to get a mask.

China's National Health Commission said on Thursday the total number of confirmed deaths from the coronavirus in the country climbed to 170, as the number of infected patients rose to 7,711.

(Reporting By Sarah Wu, Joseph, Campbell and Jessie Pang; Writing by Anne Marie Roantree; Editing by Robert Birsel)