In total there have been 13 confirmed cases of the virus being imported to the mainland -- all in Chinese nationals returning from overseas.

More than 3,100 people have died and over 90,000 have been infected worldwide.

The vast majority of cases are in China, but South Korea, Italy and Iran have emerged as the countries with the most cases outside the epicentre.

Eight Chinese nationals who worked in the same restaurant in Italy's northern Lombardy region have tested positive for the virus in eastern Zhejiang province, according to the local government.

They flew home to China from Italy last week.

There have also been four confirmed cases of infections originating in Iran -- two in Beijing and two in the northern Ningxia region -- and one case in the southern city of Shenzhen in a person who had travelled from Britain via Hong Kong.

China has been implementing a series of measures to try and prevent its containment efforts being undone by cases brought into the country.

Those arriving in the capital from virus-hit countries -- including South Korea, Italy, Iran and Japan -- must self-quarantine for 14 days, the deputy secretary of Beijing's government said at a press briefing Tuesday.

"If their destination is Beijing, everyone should be quarantined no matter whether they are Chinese or foreigners," said the official, Chen Bei.

Those with a fixed residence should stay home, he said, while those without anywhere to stay would do "concentrated medical observation at a designated hotel".

Officials in southern Guangdong province announced Tuesday they would implement similar measures, without confirming specific countries, while state media reported that Shanghai was also introducing the same rule for nations with high numbers of virus cases.

Also on Tuesday, officials in Dandong -- which borders North Korea -- announced everyone entering the city from abroad needed to be tested.

Hundreds of passengers from South Korea arriving in eastern China last week were placed in isolation after people on two flights were discovered to have fevers.

No infections have been confirmed so far.