SEOUL (AFP) - South Korea confirmed two more cases of the Middle East Respiratory Syndrome (Mers) on Friday, bringing the total number of patients infected with the potentially deadly virus to nine, though none are in critical condition, health officials said.

The infections were all traced to the original case of a 68-year-old man diagnosed on May 20 after returning from a trip to Saudi Arabia.

Mers is considered a deadlier but less infectious cousin of the Severe Acute Respiratory Syndrome (Sars) virus that appeared in Asia in 2003 and killed hundreds of people, mostly in China.

Symptoms may range from flu-like aches and pains to pneumonia and kidney failure.

The health ministry said the two new cases included a 30-year-old nurse from the hospital where the original case was reported, and a 56-year-old man who was treated there for other diseases.

About 120 people are being monitored after they were exposed directly or indirectly to the original patient, it said.

More than 20 countries have been affected by the virus, with most cases in Saudi Arabia where more than 400 have been killed since 2012