South Korea has reported three more fatalities from the Middle East Respiratory Syndrome (MERS), bringing the death toll to 23 in an outbreak that began in May.

South Korea’s Health Ministry on Thursday also confirmed four new cases, bringing to 165 the total number of confirmed infections.

The government report comes despite authorities' claims earlier in the week that the Asian country had weathered the worst of the crisis.

Seoul reported that the number of new infections had fallen steadily until Tuesday. The following day, however, eight new cases were reported, quickly dashing any hopes that the worst was over.

On Wednesday, the World Health Organization (WHO) criticized Seoul for not having the virus outbreak under control.

WHO said that the MERS outbreak was a "wake-up call" and that a lack of knowledge on the virus among medical workers and the public was a key contributing factor to its rapid spread.

The Health Ministry said it was bracing for new cases to "occur en mass in hospitals" across the country.

All of the infections have taken place in South Korea’s hospitals or medical centers.

Earlier this month, the Samsung Medical Center, one of the two epicenters of the outbreak, temporarily suspended most of its services after being identified as the source of almost half of the cases.

Over 6,500 people have been quarantined for possible infection after coming in close contact with MERS patients.

The virus is considered to be a deadlier, but less infectious cousin of Severe Acute Respiratory Syndrome (SARS), which killed some 800 people in a 2003 epidemic in Asia.

There is no vaccine or cure available for the virus yet, which, according to the World Health Organization (WHO), has a fatality rate of around 35 percent.

HDS/NN/GHN