Thai authorities took nearly four days to confirm the country's first case of Middle East respiratory syndrome, the Health Ministry said on Friday, a time lag likely to raise fears of a further spread of the deadly virus in Asia.

Thailand had confirmed its first case of MERS on Thursday, a 75-year-old businessman from Oman, just as an outbreak in South Korea appeared to be leveling off. The South Korean outbreak, which began last month, has infected 166 people and killed 24 of them.

In Thailand, the infected man arrived in Bangkok on Monday on an Oman Air flight for medical treatment for a heart ailment at a private hospital.