Diver dies at S. Korea ferry disaster site

A diver has died while on a mission to retrieve bodies from the sunken South Korean ferry.

A diver has died while working at the scene of South Korea's ferry disaster, as investigators disclosed that the ship was carrying nearly four times its legal limit of cargo.

Lee Gwang-Wook, 53, suffered breathing difficulties after reaching a depth of 25 metres, said coastguard spokesman Ko Myung-Suk.

The diver, who was making his first descent at the scene, lost consciousness and was pronounced dead in hospital.

Lee lost contact with surface controllers after five minutes in the water. His air hose was found entangled with other lines, a coastguard official was quoted as saying by Yonhap news agency.

"He was a veteran diver, who used to work up to 60 metres below the surface," his brother-in-law Kim Hyun-Chul told journalists, adding Lee had no health problems.

Scores of divers are engaged in the grim and dangerous task of finding and retrieving bodies from the sunken ship, while fighting strong currents and low visibility in silty water.

It has been 20 days since the 6825-tonne Sewol capsized and sank with 476 people on board - most of them schoolchildren - off the southwest coast.

The confirmed death toll rose to 264 on Tuesday afternoon, while 38 people remain missing.

Yonhap, citing investigators, said Tuesday the ferry was overloaded on 139 out of its 241 voyages between the western port of Incheon and the southern resort island of Jeju since beginning the service in March last year.

When disaster struck it was carrying 3608 tonnes of cargo - more than half its own weight - including 108 vehicles, the news agency quoted investigators as saying. The legal limit, according to Yonhap, was 987 tonnes.

The ferry was carrying just 580 tonnes of ballast water - only 37 per cent of the legal requirement - in order to carry more cargo. This made the ship dangerously unbalanced, Yonhap said, citing investigators.

President Park Geun-Hye on Tuesday issued a fresh apology for her government's failure to prevent the tragedy and renewed a pledge to eradicate "corruption and wrongdoing" blamed for the disaster.

"As the president who should protect the lives of the people, I don't know how to express my condolences to the bereaved families. I feel sorry and my heart is heavy with grief," she said.

"Greed for material gain prevailed over safety regulations and such irresponsible behaviour resulted in the loss of precious lives."

The ferry sinking is one of South Korea's worst peacetime disasters, made all the more shocking by the loss of so many young lives.

Of those on board, 325 were students from the same high school in Ansan city just south of Seoul.

All 15 of the surviving crew including the captain are in custody, facing charges including negligence and abandoning passengers.