Two immigration officers at Suvarnabhumi Airport, Bangkok, were positive for nCoV and could have been in contact with many passengers.

Sopon Iamsirithaworn, an official from Thailand's Department of Disease Control, said the two immigration officers were diagnosed with nCoV on March 7 and March 8, adding that they may have been exposed to multiple passengers before being detected infected.

"They don't work at the same point. It is likely they were exposed to foreign passengers or touched passports," Iamsirithaworn said. He added that one of the two employees recently joined a medical surveillance group that returned from South Korea, one of the largest Covid-19 epidemic areas in the world.

The Thai Interior Minister said on the same day that he would suspend visa exemption for Korean, Italian and Hong Kong residents. All visitors from the above areas must apply for a visa at Thai embassies and present a health certificate.

Covid-19 started in Wuhan, China in December 2019, up to now, it has appeared in 119 countries and territories, causing more than 119,000 people infected, 4,300 died.

Thailand currently records 59 positive cases of nCoV, of which one person is critical, 34 have recovered. Thai national airline Thai Airways said on March 13 that it would suspend all flights to Italy, where more than 10,000 people were infected with nCoV and more than 600 deaths.