Experts say that after the severe acute respiratory syndrome (Sars) outbreak more than a decade ago, the mainland is now well-equipped to handle the spread of infectious diseases.

It has also done its own assessment of the threat that Mers poses, the experts say.

"Since the Sars crisis, China's epidemic prevention and control system has been very sound," Dr Lu Hongzhou, of the Shanghai Public Health Clinical Centre, told the . "It is impossible for a large-scale outbreak of Mers to occur on the mainland."

The health authorities have introduced a more stringent notification system since the Sars outbreak.

The Chinese Centre for Disease Control and Prevention requires hospitals and clinics to inform higher authorities within two hours of receiving patients with suspected Mers symptoms.

Lu said the authorities decided against releasing a travel alert as the spread of Mers in South Korea had been curbed and there was no need to spark panic among mainlanders.

Based on the data, he said, Mers was spreading far slower than Sars did in 2003.

"South Korea is motivated to fight against the epidemic, and more than 2,000 people in close contact with the Mers patients are now under self-supervision or isolation. So South Korea is not so dangerous," Lu said.

Although no travel alert has been issued on the mainland, the health authorities have stepped up measures to prevent the spread of the virus and are closely watching the situation.

Watch: Asia's tourists avoiding Mers-hit South Korea

The disease control centre is stepping up its monitoring of the Mers outbreak, according to its action plan released this week.

Doctors have been instructed to pay special attention to cases of pneumonia or severe acute respiratory infections. They have also been reminded that those who contract the virus may not exhibit typical symptoms.

"The authorities feel more nervous this time round than last year when dealing with the Ebola infection," a Shanghai quarantine official said. "This is because Mers is easier to spread, and Shanghai has many more people travelling to South Korea than to Ebola-plagued West Africa."

Shanghai's quarantine authorities met last Thursday to draw up a plan in case of a Mers outbreak in the city.

Health-monitoring measures already in practice at Shanghai's ports include requiring travellers to fill in health-declaration forms and taking their temperatures.

On top of these, the plan drawn up last week introduced new measures. Quarantine officials will board planes and ships arriving directly from affected regions to conduct checks, and travellers will be told to contact the authorities if they exhibit Mers-related symptoms.

Last year, 6.1 million mainlanders visited South Korea while 4.2 million South Koreans visited mainland China. The China National Tourism Administration could not be reached for comment.

Yesterday, Hong Kong issued its red travel warning, the second-highest level in its three-step warning system. The alert advises against all non-essential travel to South Korea, and follows a health advisory for the country issued 24 hours earlier.

Taiwan last week raised its advisory travel alert for visiting South Korea to the second of its four alert levels.

Yesterday, the island said it had cooperated with the mainland and Hong Kong by sharing information about the Mers outbreak in South Korea.

It remained on high alert in dealing with the issue, said a spokeswoman for the Centre for Disease Control under Taiwan's Health and Welfare Ministry.

Taiwan has signed information-sharing and other cooperation programmes with both the mainland and Hong Kong to fight the cross-border epidemic.

Japan has set up task forces at its diplomatic missions in South Korea to help its nationals there handle the spread of the virus, Japanese foreign minister Fumio Kishida said.