China is searching for 13 people who came into contact with the first person to enter the country with the MERS virus, health officials said, adding that 64 had already been quarantined.

Eleven people who travelled on a bus with a 44-year-old man from South Korea who entered China with the disease are among the 13 that are being sought, health officials in the southern province of Guangdong said.

The man flew to Hong Kong from Seoul on Tuesday last week, before later travelling overland to Huizhou in Guangdong by bus, ignoring the advice of doctors to stay at home, the China Daily newspaper said Monday.

He is currently under quarantine, where "his vital signs are stable, and his heart rate and blood pressure normal", it added.

None of those who have been quarantined are "appearing unwell", Guangdong's Health and Family Planning Commission said late Sunday in an online post.

"(We) still need to get 13 people, among them 11 bus passengers," the post on Sina Weibo, a Chinese version of Twitter, said. It added that no passenger records were available.

MERS, or Middle East Respiratory Syndrome, can cause symptoms ranging from flu-like aches and pains to pneumonia and kidney failure.

It is considered a deadlier but less infectious cousin of Severe Acute Respiratory Syndrome (SARS), which killed hundreds of people when it appeared in Asia in 2003.

South Korean President Park Geun-Hye on Monday scolded health officials for their "insufficient" response to an outbreak of the virus in the east Asian country which has seen 18 people become infected.

It came after South Korean health officials were criticised for allowing the infected man to travel overseas despite warnings from doctors.

In Hong Kong, 18 people -- who sat near him on the flight from Seoul -- have been quarantined, the city's Centre for Health Protection has said.

"The possibility of widespread human-to-human infections is remote," China Daily added, paraphrasing Lin Jianfeng, a director in charge of infectious disease prevention at the Guangdong Center for Disease Control and Prevention.