Three more cases of the Middle East Respiratory Syndrome (MERS) were reported in South Korea on Tuesday, raising the total number of cases in the country to 175. The land, infrastructure and transport ministry also said in a statement on Tuesday that those currently in isolation are barred from traveling in domestic flights.

Two of the three new people, diagnosed with the disease, were already under isolation as suspected cases. The way the third person contracted the disease was unclear, Yonhap reported. However, officials suspect that the third patient may have been infected by an ambulance driver or a paramedic exposed to MERS patients.

Since the first case of MERS was reported in the country in May, 27 people have died from the respiratory virus. Over 13,000 people have been quarantined and 10,718 people have been released from isolation after they showed no signs of infection during the maximum incubation period of 14 days.

The South Korean government, which is struggling to curb the spread of the fatal disease, has banned people under quarantine from using domestic air services, it announced on Tuesday. The decision was taken after a male patient, who had developed symptoms, but had not been diagnosed with the disease, traveled to the southern resort island of Jeju from Seoul, according to Yonhap.

The disease currently does not have a vaccine or treatment and has a 15 percent fatality rate in South Korea. Hospitals in the country are considered as the main points of contraction of the disease. Lee Jae-yong, the 47-year-old heir to the Samsung business empire, apologized Tuesday to the families of MERS patients and the victims on behalf of the Samsung Medical Center. Of all the MERS cases in South Korea, 85 were patients, relatives, staff or visitors at the Samsung hospital in Seoul.

"Our Samsung Medical Center could not stop the infection and the spread of MERS, causing so much pain and worry for the public," Lee said Tuesday in his first public speech since taking over the Samsung Foundation that owns the hospital from his ailing father last month, according to the AP, adding: "I bow my head to apologize."

The apology follows an editorial last week in South Korea’s largest newspaper Chosun Ilbo, which called for an investigation into the alleged ties between government and the Samsung group. The editorial also questioned why health officials in the country did not oversee the hospital’s efforts to curb the disease, the AP reported. The business conglomerate has interests in consumer electronics, shipbuilding, insurance, construction and amusement parks.