South Korea confirmed two additional cases of the Middle East Respiratory Syndrome on Friday, raising the number of patients diagnosed with the virus to nine.

The two were found to have been infected with the potentially fatal disease from a 68-year-old patient, the country's first confirmed MERS case, according to the health ministry.

One of them was a 30-year-old female medical staff who treated the first confirmed MERS patient, while the other, who is 56 years old, stayed at the same hospital ward as the first patient, the ministry said. 

The medical staff was among those who have been in quarantine.

MERS is a viral respiratory illness that is fairly new to humans, with only 1,142 reported cases in 23 countries since the first case was confirmed in Saudi Arabia in 2012. There currently is no vaccine or treatment for the disease, which has a very high fatality rate of 40.7 percent.

The latest cases raised the number of people infected with the potentially deadly virus to nine, eight of whom were known to have come in contact -- director or indirect -- with the patient who was first confirmed on May 20.

The ministry said that it is closely monitoring a total of 120 people who might have contacted MERS patients to prevent the spread of the virus, though no secondary infections have been reported.

Meanwhile, as the health conditions for the 71-year-old man who tested positive for MERS on Thursday deteriorated sharply, medical staff inserted tube into the patient to support his breathing, according to the ministry. (Yonhap)