The Mers outbreak that has spread through health facilities in South Korea may have peaked, although two hospitals that treated people with the deadly respiratory disease have been sealed off, officials said.

Middle East Respiratory Syndrome (Mers) has infected 126 people in South Korea and killed 13 since it was first diagnosed just over three weeks ago in a businessman who had returned from a trip to the Middle East. Just four new cases were reported on Friday.

The Health Ministry announced two more deaths in elderly patients who had been suffering respiratory ailments before they tested positive for the virus.

The outbreak is the largest outside Saudi Arabia, where the disease was first identified in humans in 2012, and has stirred fears in Asia of a repeat of a 2002-2003 scare when Severe Acute Respiratory Syndrome (Sars) killed about 800 people worldwide.

The 68-year-old man who brought Mers back to South Korea visited several health centres for a cough and fever before he was diagnosed, leaving a trail of infection in his wake.

The two sealed-off hospitals, with at least 133 patients and staff, would be closed for at least the next 11 days, given the incubation period of the virus, officials said.

"No patients can get out of their rooms," said a city government official in the capital, Seoul, where one of the hospitals is located, declining to be identified.

"Nurses in protective gear are giving them food. No one can get in from outside."

All but one of South Korea's cases have been confirmed as originating with the businessman, who was diagnosed with Mers on May 20, and occurring in health centres, and the last one is likely to be confirmed as such too, the health ministry said.

WORST OVER?

Mers is caused by a coronavirus from the same family as the one that caused Sars. It is more deadly than SarsARS but does not spread as easily, at least for now. There is no cure or vaccine.

World Health Organization (WHO) experts are in South Korea working with the government and Saudi Arabian health officials are meeting authorities on Friday.

The four new cases reported on Friday marked the lowest daily increase in 11 days, raising hope the worst might be over.

"The signs are beginning to look promising," Columbia University Medical Center professor of epidemiology, Stephen Morse, told Reuters from New York. "I'm hopeful it's beginning to decline, but there are still patients."

The number of people in quarantine, either at home or in medical facilities, also declined for the first time, by 125 to 3,680, the ministry said.

The incubation period for many people exposed to infected patients is ending, which should mean a decline in new cases, said Kangnam Sacred Heart Hospital infectious disease expert, Jacob Lee, in Seoul.

"There may be a third wave from hospitals that Mers patients had stayed at but it won't spread as much as it has," Lee said.

Alarm has spread in the region even though only one case has been reported outside South Korea in this outbreak, that of a South Korean man who travelled to China via Hong Kong despite authorities suggesting he stay in voluntary quarantine at home.

The central bank cut interest rates on Thursday in the hope of softening the blow to an economy already beset by slack demand and plunging visitor arrivals.

US President Barack Obama telephoned President Park Geun-hye, who has postponed a visit to Washington to manage the outbreak, to say he was prepared to lend all support to help fight the disease, her office said.

South Korea's new cases bring the number of cases globally to 1,275, based on WHO data, with at least 452 related deaths. - Reuters