A diver has died during the search operation for victims still missing after last month's South Korean ferry disaster.

The diver lost radio contact five minutes after diving to fix guideline ropes on the fifth deck of the sunken ferry, according to Ko Myung-seok, spokesman for the government's emergency task force.

He was unable to breathe by himself when he was brought to the surface. His death was later confirmed at hospital.

The diver had been working for Undine Marine Industries, the company brought in to lead search efforts on the Sewol ferry.

The ferry capsized and sank about 12 miles off the southwest coast of South Korea on 16 April with 476 passengers and crew on board.

Among the passengers were 339 children and teachers on a high school outing to the southern island of Jeju.

Only 174 people were rescued. The confirmed death toll is 263, with 39 still missing.

An investigation is ongoing amid rising indignation over the government's handling of the disaster.

President Park Geun-hye voiced criticism today of the role played by the ferry operator and government officials.

"Safety rules that must be observed were not followed because of worldly desires and irresponsible acts that tolerated those injustices have resulted in death," she said during her address at a temple in Seoul to celebrate Buddha's birthday.

She promised to fundamentally change national policies and systems to improve safety and to clean up malpractices to ensure businesses and government officials comply with requirements.

President Park visited the families of the ferry victims yesterday in Paengmok port in Jindo for the second time since the tragedy.

Her approval rating has slipped to 53%,down 12 points, according to Seoul-based polling company Realmeter.