Many of the bodies pulled from the wreck of a South Korean ferry have broken fingers, indicating the desperate final moments of the mostly young victims, according to South Korean media.

So far 150 bodies have been pulled from the wreck of the Sewol ferry, which hit rocks off South Korea's south coast last week.

Of the 476 passengers and crew on board, 339 were children and teachers on a high school outing. Only 174 people have been rescued and the remainder are presumed to have drowned.

Divers sent into the wreck are having to feel for the bodies with their hands in a maze of cabins, corridors and upturned decks.

The divers, with oxygen and communications lines trailing, can only see a few inches in front of them.

Local media reports say many of the bodies found in the last two days have broken fingers, presumably from the children frantically trying to climb the walls or floors to escape in their last moments.

"We are trained for hostile environments, but it's hard to be brave when we meet bodies in dark water," diver Hwang Dae-sik told Reuters, as the funerals of 25 students were held near the capital, Seoul.

Mr Hwang said his team had retrieved 14 bodies so far.

"We have to touch everything with our hands. This is the most gruelling and heartbreaking job of my career," he said.

In a rare move, the disaster prompted reclusive North Korea - which is still technically at war with the South and routinely threatens the South with destruction - to send a message of sympathy.

"We express condolences for the missing and dead, including young students, from the sinking of the Sewol," a South Korean Unification Ministry spokeswoman quoted the message as saying.

Fresh raids over business links to capsized ferry

Prosecutors investigating the disaster raided the home of Yoo Byung-un, the head of a family that owns the Chonghaejin Marine Co Ltd, the company that operated the Sewol ferry.

They also raided his son's home and the office of a church with which Mr Yoo has been associated, said a prosecutor who did not want to be identified.

The finances of Chonghaejin and its complex share structure have come into the spotlight in recent days. Mr Yoo was jailed for fraud for four years in the early 1990s.

But it was not immediately clear how big a development this was. Korean police and prosecutors often make dramatic raids to show that progress is being made in a high-profile case.

Underwater, at the site of the sunken Sewol, divers are able to work for nearly an hour at a time as long as their oxygen lines do not snag on sharp corners of the ship's internal structure.

When they use cumbersome oxygen tanks on their backs instead, they can work for about 20 minutes before an alarm bell sounds.

Most of those who survived made it out on deck and jumped into rescue boats, but many of the children did not leave their cabins, after being told to stay put as the ship began to sink.

Captain Lee Joon-seok, 69, and other crew members have been arrested on negligence charges. Lee was also charged with undertaking an "excessive change of course without slowing down".

Lee was not on the bridge when the ship turned. Navigation was in the hands of a 26-year-old third mate, who was in charge for the first time on that part of the journey, according to crew members.

The wife of one crew member under investigation who did not wish to be identified quoted her husband as saying: "I should have died out there."

"He told me that he was taking some rest as he had finished his shift. He fell from his bed and struggled to open the room door to get out. He said he didn't go to the steering house to meet up with rest of the crew. Rather he was found by coastguards and was rescued.

"My husband didn't get along with other crewmen, but he told me that Captain Lee was someone comfortable and extremely calm. He said Captain Lee was like no other: he didn't drink much, although he did smoke."

Reuters