The United States warned that Americans should reconsider visiting China, while the United Kingdom advised against all but essential travel to mainland China. South Korea also advised its citizens to stay away.

Facebook Inc became the first significant US company to announce a travel suspension after the US government's warning, saying it had asked employees to halt non-essential travel to mainland China and to work from home if they had travelled there.

Chicago-based United Airlines said it was suspending 24 US flights to Beijing, Hong Kong and Shanghai between February 1 and February 8 due to a significant drop in demand.

Europe's biggest bank, HSBC Holdings PLC, banned all staff travel to Chinese-ruled Hong Kong for two weeks and mainland China until further notice, according to an internal memo seen by the Reuters news agency.

The British-based lender, which has the largest presence among foreign banks in China, also asked staff who have recently visited the country to undergo a self-imposed 14-day quarantine. The virus has an incubation period of up to 14 days.

US rival Goldman Sachs Group Inc imposed similar measures, according to a memo seen by Reuters.

In South Korea, home appliances maker LG Electronics Inc put a complete ban on travel to China and has advised employees on business trips in the country to return home as quickly as possible, a company spokeswoman said.

South Korean chipmaker SK Hynix Inc said it was urging employees to avoid all non-essential travel to China, while banking group Standard Chartered PLC restricted travel to mainland China and Hong Kong.

In Germany, auto supplier Webasto, which has 11 sites in China, including in Wuhan, has halted all corporate travel to and from China after an employee was infected.

Japan's Honda Motor Co Ltd said it recommended employees avoid travel to China, while Nissan Motor Co Ltd said it plans to evacuate its Japanese staff and their families in Wuhan via a government-chartered flight.

Toyota Motors Corp said it would halt operations in China until February 9, having already restricted travel to Hubei province, based on guidlines from Japan's foreign ministry.

'Falling travel demand'

Aside from United, other airlines said they were adjusting schedules as companies reassessed the risk of travel to China.

South Korean budget carrier Air Seoul said it will halt all flights to China, while Taiwan's China Airlines Ltd rescheduled and cancelled some flights to China until February 10.

Taiwan's Eva Airways Corp also said some flights to China may be cancelled.

Air Canada said it was cancelling some of its 33 weekly flights to China, and Germany's Lufthansa pointed to subdued bookings to and from the country.

Hong Kong's Cathay Pacific Airways Ltd said it would be progressively reducing capacity to and from mainland China by 50 percent or more from January 30 to the end of March, in line with a government directive as well as market demand.

International SOS, a medical and travel security services firm that advises companies on travel, said its guidance, for now, was that business travel to China outside Wuhan's province of Hubei could continue.

But this could be updated if there were significant flight cancellations throughout China and more disruptions to ground transport, International SOS Regional Security Director James Robertson said.