The captain in charge of the Sewol ferry when it sank told a South Korean court Wednesday that he "deserved the death penalty" but denied sacrificing passenger's lives to save his own.

Lee Joon-Seok, on trial for murder in the city of Gwangju, was vilified after the April disaster for abandoning the stricken ferry while hundreds were still trapped inside.

More than 300 people perished, most of them school children in a tragedy that stunned South Korea.

The captain and many crew members were among the first to climb onto rescue boats.

Video footage taken from the phones of those who perished showed increasingly worried students patiently waiting in their bunks as messages were broadcast over the ship's tannoy telling them to stay where they were despite the ferry listing heavily.

But Lee said his passenger evacuation orders had fallen on deaf ears and denied accusations by the prosecution that he sacrificed the lives of his passengers to save himself.

"I sincerely apologise to the victims and their relatives and I will pray for them for the rest of my life", Lee said at his trial, according to Yonhap news agency.

"I think I deserve a death penalty for what I have done. But I never thought for a moment to sacrifice the passengers (to save my own life)".

"No matter how God helps me, I know I won't be able to leave the prison before I die. But I cannot give my children and grandchildren a bad name as a murderer's relatives", Lee added.

He insisted he had told a crew member to broadcast a passenger announcement that passengers should wear life jackets and jump into the sea, around five minutes before the first rescue boat arrived.

The message was never relayed, he added. But Lee he was unable to provide any evidence that he issued this instruction.

The disaster caused outrage in South Korea, knocking the entire country off its stride and triggering widespread public anger as it emerged that incompetence, corruption and greed had all contributed to the tragedy.

Captain blames ship owners

Lee has insisted that the ferry owners are the real culprits of the disaster as it was their decision to consistently overload the vessel and commission an illegal redesign.

His murder prosecution comes as the son of the ferry's owner also faces a separate trial for embezzlement.

Prosecutors on Wednesday called for four years in prison for Yoo Dae-Kyun, the eldest son of the now deceased South Korean tycoon blamed for the ferry disaster.

Yoo, 44, who has been charged with syphoning off more than $7 million from Chonghaejin Marine Co., the operator of the stricken ferry, and its six sister companies between 2002 and late last year.

Three other family members -- Yoo's mother and two uncles -- have also been arrested on charges of embezzlement from the business group including Chonghaejin Marine.

Yoo's sister, Yoo Sum-Na, 48, is currently fighting extradition from France on similar charges.

The badly decomposed body of Yoo's father, Yoo Byung-Eun, who in addition to his substantial business interests also ran a religious group, was found in June. He had been the target of a massive manhunt connected to the ferry sinking.

"I am sorry," Yoo said to the court before bowing to the judge, the prosecutors and the audience in turn.

Yoo's defence lawyer has called for leniency in the sentencing, expected on November 5, stressing that Yoo will dispose of all his assets to help compensate for the victims.

Prosecutors are also questioning one of the late Yoo's key aides -- who was repatriated from the US Tuesday -- over assets the Yoo family may be hiding.

Kim Hae-Kyung, 52, who was arrested in Virginia in September, is suspected of involvement in the embezzlement of about $23 million from the religious organisation headed by the elder Yoo.

Lee, 69, and three senior crew members are accused of "homicide through wilful negligence" -- a charge that can carry the death penalty.