SEOUL (Reuters/AFP) - Two more patients with Middle East respiratory syndrome (Mers) virus have died, South Korea's Health Ministry said on Friday, bringing the total number of fatalities to 31.

The ministry also reported one new case, taking the total to 181 in an outbreak that is the largest outside Saudi Arabia. Of them, 81 have recovered and 69 are still being treated, including 13 listed in critical condition.

The new fatalities had pre-existing health problems, according to the ministry. They were both women, aged 79 and 80, and both had existing health conditions. Most of the deaths have been elderly patients or those who had existing illnesses.

The new case involved a doctor at Seoul's Samsung Medical Centre, the hospital to which nearly half of all infections have been traced back.

The hospital earlier this week decided to extend indefinitely a 12-day suspension of normal services as patients, doctors and visitors continued to be diagnosed with the disease.

The number of people in isolation, meanwhile, rose to 2,931.