SEOUL, June 3 -- More than 1,300 South Koreans have been put under self or institutional quarantine due to suspected infection from the Middle East Respiratory Syndrome (MERS), the country's health ministry said Wednesday.

Kwon Joon-wook, head of the central headquarters for management of the MERS, told a press briefing that 1,312 people were on the isolation list of the health authorities.

The number of people placed under quarantine jumped from 791 on Tuesday to 1,364 Wednesday. Among them, 52 people were freed from the isolation as they showed no specific symptom during the incubation period of two weeks.

About 1,200 people were on the self-quarantine list, which means that they refrain from going outside and stay at home under the regular check of the health authorities.

Some 100 people were placed under isolation in the government- designated medical institutions.

Among the total 398 MERS-infected suspects, 29 have been tested positive as of Wednesday. One was diagnosed with the MERS in China.

One more tertiary infection case was reported Wednesday, a day after two cases were identified. Two people died of the viral disease on Monday and Tuesday.

The MERS is a respiratory illness caused by a new type of corona-virus that is similar to the one causing Severe Acute Respiratory Syndrome (SARS). There is so far no vaccine or treatment for the disease, with its fatality rate reaching 40.7 percent.

The first case was spotted in Saudi Arabia in 2012. The World Health Organization has reported more than 1,000 cases of MERS globally and more than 400 deaths.