SEOUL (REUTERS) - The heir-apparent of South Korea's massive Samsung Group apologised in a nationally televised address on Tuesday for failing to stop the spread of Middle East Respiratory Syndrome (Mers) at a Seoul hospital run by a group foundation.

About half of the 175 Mers cases in South Korea have been traced to Samsung Medical Centre, tarnishing the image of one of the country's most prestigious hospitals. The South Korean outbreak is the largest outside Saudi Arabia and has claimed 27 lives.

Jay Y. Lee, the only son of Samsung Group head Lee Kun Hee, said the conglomerate would do everything it could to stop the outbreak and revamp care at Samsung Medical Centre, located in Seoul's wealthy Gangnam district.

"Our Samsung Medical Centre was unable to stop the Mers infection and its spread, and caused too much suffering and concern to the public. I bow my head in apology," Lee said in rare public remarks for the man set to lead South Korea's largest family-run conglomerate, or chaebol. "We have failed to live up to the expectation and trust of the public," he said.

Lee had previously visited the hospital during the outbreak but without making any statements. The hospital has also apologised for the outbreak.

South Korea's Mers outbreak, traced to a businessman who returned last month from the Middle East, has scared off tourists and dealt a blow to the economy as consumers stay home.

Its health ministry said the outbreak appears to have levelled off, with new infections reported in recent days in the low single digits, including three on Tuesday.

Lee, who turned 47 on Tuesday, became vice-chairman of group flagship Samsung Electronics Co Ltd in 2012 and is expected to take the reins of that company and the overall group. His father has been hospitalised at Samsung Medical Centre since a heart attack last year.

"My father has been lying at this hospital for more than a year," Lee said. "I understand even to a small degree the worry and pain that patients and their families have experienced," he said.

Samsung Medical Centre has been criticised after it was revealed that a Mers patient had been in its emergency ward for two-and-a-half days before being diagnosed, coming into contact with nearly 900 people, including staff.

It later suspended most services after an emergency ward orderly tested positive for the virus after working for a number of days despite having symptoms and coming into contact with more than 200 people.

South Korea's health ministry said on Tuesday that 54 people who had tested positive for the virus have recovered and been discharged from hospital.

Most of the 27 deaths in South Korea were elderly patients or people who had existing illnesses.