Family members of hundreds of children who drowned when a ferry sank last month staged a vigil outside the presidential palace in South Korea today demanding those responsible be punished.

President Park Geun-hye did not emerge to meet the 400 relatives who had marched in darkness to her Blue House office in Seoul.

She sent two of her top aides to listen to their demands, including the sacking of a state broadcast official for insulting comments.

Clutching memorial portraits of their children and brothers and sisters, the family members were prevented by police from nearing the Blue House.

They sat in the middle of the road where they sobbed, wailed and shouted in anger.

"We had to watch our kids go from being alive to being killed," said Oh Tae-won, whose teenage daughter was among the victims. "This is a massacre, not an accident, and they are two different things."

The Sewol, overloaded and travelling too fast on a turn, sank off the southwest coast on a routine journey from Incheon on the mainland to the southern holiday island of Jeju.

Hundreds of children and teachers on a high school field trip were killed. 

Only 172 people have been rescued of an estimated 476 passengers and crew on board.

The confirmed death toll today is 273.

Some of the crew, including the captain, were caught on videotape abandoning the ferry.

Meanwhile, the children were told again and again to stay put in their cabins where they awaited further orders.

They paid for their obedience with their lives.

Families' grief turned to anger late yesterday when an executive at a state broadcaster KBS was quoted as comparing the dead and missing to the number of people who die in car accidents in the country.

KBS's head of news operations resigned today to take responsibility.

The families outside the Blue House dispersed after the chief executive apologised in person, media said.