South Korea confirmed five additional cases of the Middle East Respiratory Syndrome (MERS) Wednesday, bringing the total number of people diagnosed with the potentially deadly disease here to 30, the Korean news agency Yonhap said.

Four of the five people newly diagnosed with MERS are believed to have been infected after coming in close contact with the country's first-ever patient, who allegedly caught the disease while traveling to the Middle East in mid-April, according to the Ministry of Health and Welfare.

The ministry said the four new patients came in contact with the first patient at an undisclosed hospital in mid-May.

The country also confirmed an additional case of tertiary infection in a 60-year-old male who had shared the same hospital room with one of the patients diagnosed earlier.

The case marked the third of its kind in South Korea and reportedly in the world.

The health ministry earlier said no tertiary transmission of MERS had been reported throughout the world, a reason it had long insisted on isolating only the people who had come in close contact with the first patient.

Shortly before the country confirmed two cases of tertiary transmission Tuesday, the government changed its stance, largely as a precautionary measure, and began isolating those who have come in close contact with anyone diagnosed.

The number of people in isolation for fear of possible infection came to 1,312 as of Wednesday morning, according to the health ministry.

The number nearly doubled from 682 as of early Monday, but ministry officials have said the number may quickly multiply following the confirmation of tertiary transmissions.

"We are now identifying people newly subject to isolation in relation to the latest confirmed cases. Once the process is completed, the number of people in isolation may have multiplied by a significant number," an official said earlier while speaking on condition of anonymity.