China is facing a heightened risk of more MERS cases because of frequent contacts with areas of the Middle East and South Korea that have been hit hard by the potentially lethal viral infection, the nation's top health authority said.

Mao Qun'an, spokesman for the National Health and Family Planning Commission, said on Wednesday that China faces a "substantially increased risk" of more imported cases.

Mao made his remarks at a news conference as the condition of China's first confirmed MERS patient, who is from South Korea, was reported to be in stable condition at a hospital in Guangdong province.

"Stakeholders like the border control and quarantine authorities and health facilities have been well-prepared for an outbreak response. Inspections of disease control and treatment work will be performed at high risk regions like south Guangdong province and the capital of Beijing," he said.

MERS is a respiratory illness caused by a coronavirus, similar to SARS. The first human case emerged in Saudi Arabia in 2012. There is no vaccine or treatment for the virus, which has a fatality rate of about 40 percent.

Also on Wednesday, China's General Administration of Quality Supervision, Inspection and Quarantine ordered border quarantine staff to refer suspected cases to designated hospitals for further investigation.

Visitors from affected areas should honestly report symptoms like fever, coughing and difficulty breathing, it said.

Chinese who are heading to affected areas should avoid visiting local hospitals and having contact with bats and single-hump camels.

The World Health Organization recommended on Wednesday that people who have had close contact with MERS patients not to travel during the quarantine period.

Also, infection prevention and control measures should immediately be strengthened in all facilities across the country, the WHO said.

He Xiong, deputy director of the Beijing Center for Disease Control and Prevention, said that outbreak details in South Korea have not been fully disclosed. He urged South Korea to provide more timely and detailed information about the outbreak.

China will consider issuing outbound travel alert if "we detect infection among returned travelers from affected areas", He said.

A Chinese woman living in South Korea has tested positive for MERS, the National Health and Family Planning Commission said on Wednesday.

The patient, 64, had come into close contact with a confirmed MERS patient at a South Korean hospital where she works. She is now in an isolation ward undergoing treatment.

Zhong Nanshan, a respiratory expert in Guangdong, said a massive outbreak of MERS in China is unlikely given a lack of evidence of sustained human-to-human transmission of the virus.