Media playback is unsupported on your device Media caption Victim's father Kim Byung-kwon: "I should have told her to jump off the boat"

The South Korean ferry that sank on Wednesday was steered by an inexperienced third mate who had never navigated the challenging waters where the accident occurred, prosecutors say.

The third mate is in custody along with the captain and another crew member.

Coastguards confirmed on Saturday that divers had retrieved 13 more bodies from the ferry, bringing the number of confirmed dead to 46.

Some 174 passengers have been rescued, with another 256 still missing.

Recovery operations may take two months, officials say, as the divers battle strong currents and poor visibility to reach the sunken vessel.

"Divers broke through the window of a passenger cabin... and pulled out three bodies," a coastguard official told the AFP news agency on Saturday.

All three were wearing lifejackets, he added.

The Sewol, carrying 476 passengers and crew, capsized during a journey from the port of Incheon in the north-west to the southern holiday island of Jeju.

Ferry captain Lee Joon-seok, 69 - who was not initially on the bridge - faces charges including negligence of duty and violation of maritime law.

'Unfamiliar' waters

Late on Saturday prosecutors said that the third mate had been steering the ferry in waters that were unfamiliar to her.

Asked how long the rescue operation was likely to continue, Shin Won-nam, the head of the Emergency Management Centre, told reporters that it could take weeks, if not months.

"We are not sure about it. But according to the experts, the rescue may last one or two months," he said.

He added that it was very unlikely someone trapped alive after the sinking could survive if it took this long.

Relatives have begun providing DNA samples to help identify the dead.

Media playback is unsupported on your device Media caption Sewol Ferry Captain Lee Joon-seok: "I am sorry to the people of South Korea"

Investigations are focusing on a sharp turn the vessel took before it started listing and whether an evacuation order could have saved lives.

Footage from the ship appeared to show instructions from crew members for passengers to remain on board even as it tilted dramatically to one side.

Mr Lee says he delayed the evacuation, fearing passengers would "drift away".

He was shown on television on Saturday following his arrest.

"I am sorry to the people of South Korea for causing a disturbance and I bow my head in apology to the families of the victims," he said.

Image copyright AFP Image caption Funerals have already begun for the victims

Image copyright AFP Image caption Relatives of the missing passengers were shown underwater footage of divers reaching the vessel

Image copyright Reuters Image caption Rescue workers continued to search for survivors through Friday night

Image copyright Reuters Image caption Search teams installed buoys to mark the position of the ship after it disappeared under the surface on Friday

Some experts believe the ship's tight turn could have dislodged heavy cargo and destabilised the vessel, while others suggest the sinking could have been caused by a collision with a rock.

Messages and phone calls from those inside painted a picture of people trapped in crowded corridors, unable to escape the sharply-listing ferry.

Officials say air has been pumped into the ship to aid any people trapped inside and to help refloat the vessel.

But they say cranes at the site will not be used until they are certain no-one inside is alive.

Nets around ferry

The South Korean coastguard says conditions around the vessel are dangerous, with fast currents, poor visibility and high waves hampering the operation.

Media playback is unsupported on your device Media caption The BBC's Jonathan Head says video filmed by divers was shown to relatives

Choi Sang-hwan, deputy director of the national coastguard, said nets would be placed around the sunken ferry to prevent any bodies drifting away.

Some 350 of those on board were students from Danwon High School in Ansan, a suburb of Seoul, who were on a school outing when the ferry sank.

Hundreds of relatives of those on board have been camping at a gymnasium on Jindo island near the scene of the disaster.