HONG KONG - Two Korean nationals having close contact with a Middle East Respiratory Syndrome (MERS) patient who passed through Hong Kong are refusing to go into quarantine, said Health Secretary Ko Wing-man.

The two Korean nationals are among 18 plane passengers who sat close to the MERS patient, probably against medical advice, Ko said.

Hong Kong's health authorities have made plans for the 18 plane passengers to go into quarantine for two weeks at the Lady MacLehose Holiday Village in Sai Kung. But two of them are refusing to be tested and isolated, Ko said, adding that authorities can only contact them by phone.

Ko said the Immigration Department is tracking them down, and the government could force them to be quarantined using Hong Kong laws.

As the incubation period of the disease could be more than ten days, the two could spread the deadly virus, he added.

The 44-year-old South Korean MERS patient flew from Seoul to Hong Kong on Tuesday before heading to the Chinese mainland by bus. He is thought to have contracted the disease from his father, and traveled against the advice of doctors. He is now at a mainland hospital in Huizhou of Guangdong Province, south China.

MERS was first identified in humans in 2012. The virus is similar to that which causes Severe Acute Respiratory Syndrome, or SARS.

The World Health Organization has reported more than 1,000 cases of MERS globally and more than 400 deaths.