SEOUL (REUTERS) - South Korea's health ministry reported on Saturday nine more cases of Middle East Respiratory Syndrome (Mers), raising the total to 50, but said one patient had recovered and became the first to be discharged from hospital.

The outbreak first reported on May 20 has claimed four lives and stirred public fear as the government was blamed for an ineffective initial response that allowed one man who had returned from Saudi Arabia to infect more than half the rest.

All nine new cases were traced to the initial patient, the health ministry said, calling them health care associated infections. They included one healthcare worker at a hospital that treated an infected patient, it said.

There has been no sustained human-to-human transmission, but the worst case scenario is the virus changes and spreads rapidly, as Severe Acute Respiratory Syndrome (Sars) did in 2002-2003, killing about 800 people around the world.

Mers was first identified in humans in 2012 and is caused by a coronavirus from the same family as the one that triggered Sars. But Mers has a much higher death rate at 38 percent, according to World Health Organisation (WHO) figures.

South Korea's new cases bring the total number globally to about 1,194, based on WHO data, with at least 443 related deaths.