South Korea has confirmed nine more cases of the MERS virus, which has killed four people, but said it did not represent a spread of the outbreak as the infected were already in quarantine.

The additional cases on Saturday brought the total number of people infected with the virus to 50.

All are among the already-listed and quarantined people of more than 1660 who came into contact with those infected before the first case was diagnosed in South Korea on May 20, the health ministry said.

"The nine people contracted the virus (in three different) hospitals and there is no evidence to suggest any transmissions in communities outside hospital settings," it said in a news statement.

Kwon Joon-Wook, a senior official of the ministry, told journalists on Saturday the 68-year-old man who was the first case and his wife who contracted the virus from him have been cured and were released from hospital on Friday.

Two others were waiting to be released, he said.

Four people have died since the 68-year-old man was diagnosed on May 20 after a trip to Saudi Arabia.

More than 1660 people who may have been exposed to the virus have been placed under varying levels of quarantine.

The outbreak has forced hundreds of schools to shut their gates, thousands of people to cancel travel plans and dealt a blow to many businesses as people were told to avoid large crowds.

The World Health Organisation (WHO) said on Friday it would send a team of experts to South Korea for a joint mission with the government in collecting information of the outbreak.

The team is expected to arrive here as early as next week, the ministry said.

The WHO has said it expects more infections in South Korea, while stressing there was "no evidence of sustained transmission in the community".