Thai authorities on Friday said two relatives of an Omani man found to have MERS were being tested for the deadly virus in the kingdom.

Thailand, a booming medical tourism hub popular with Middle Eastern patients, on Thursday confirmed the Omani, 75, had MERS, days after he arrived at a Bangkok hospital for treatment for a heart condition.

On Friday the Omani patient was "getting a bit better", said Thailand's Public Health Minister Rajata Rajatanavin at a press conference on the outskirts of Bangkok.

But two of his male family members, among three relatives with whom he travelled to Thailand on Monday, were being tested for MERS after one was found to have a cough and the other a fever.

"We have taken their samples for laboratory testing," Rajata told reporters, adding the results should be available Friday evening.

The relatives are in quarantine at the Bamrasnaradura Infectious Diseases Institute in Nonthaburi province outside the Thai capital where the Omani patient is also being treated.

Middle East Respiratory Syndrome (MERS) has spread at a rapid pace in South Korea since the first case was diagnosed on May 20, infecting 166 people in what is the largest outbreak outside Saudi Arabia.

The MERS case was the first recorded in Thailand and also the first in Southeast Asia since the South Korean outbreak.

Thai authorities are monitoring a further 85 people who have been in contact with the Omani, including those on board his flight to Bangkok, at hospital or in their homes, a health ministry spokesman told AFP Friday.

Authorities are also still trying to locate one of the 21 "high risk" people identified on that flight -- a person from the northeastern Thai province of Buriram.

In a bid to contain the deadly virus Thai officials have installed thermoscans at airports to detect passengers with fever and are also handing out information pamphlets about MERS in Thai, Arabic and English.

Rajata also said that Thailand has informed airlines about the transit passengers and crew who are no longer in the country but deemed at risk after sharing the flight with the Omani man.

Earlier government spokesman Sunsern Kaewkumnerd told AFP authorities were confident that Thailand's measures to contain the virus were "under control".

According to World Health Organization data MERS cases have been reported in four Asian countries before Thailand since the virus first surfaced in Saudi Arabia in 2012.

Malaysia and the Philippines reported cases before the South Korean outbreak in May, while China reported a person with MERS who had travelled to the country after recent exposure in South Korea, according to a WHO statement.