Scores missing after Republic of Korea vessel overturns and sinks off country's southwestern coast; Coast Guard and navy teams seek survivors after 164 rescued

Nearly 300 people remained missing on Wednesday night after a ferry sank off the Republic of Korea in the morning, the Coast Guard said, in what could be the country's biggest peacetime disaster in nearly 20 years.

The ferry Sewol was carrying 459 people, of whom 164 were rescued, Coast Guard officials said.

There were no Chinese passengers on board, the Chinese embassy said in Seoul.

News agency reports said at least four people were confirmed dead after the ferry listed heavily onto its side and capsized in apparently calm conditions off the southwestern coast.

The ROK's Ministry of Security and Public Administration earlier reported that 368 people had been rescued and that about 100 were missing, but it later described those figures as a miscalculation.

The cause of the disaster was not immediately clear, although some survivors reported that the ship appeared to have been involved in some sort of impact.

"The ship went 'boom' and there was a noise of cargo falling," said Cha Eun-ok, who added that she was on deck taking photographs when the disaster happened.

"An onboard announcement told people to stay put ... people who stayed are trapped," she said in Jindo, the town nearest the accident scene.

Several other survivors spoke of hearing a loud impact before the ship started listing and rolling on its side.

Within two hours, the Sewol was lying on its port side. Soon after, it had overturned, with only the forward part of its white and blue hull showing above water.

Coastguard vessels and fishing boats scrambled to the rescue, with television footage showing rescuers pulling passengers in life vests out of the water as their boats bobbed beside the ferry's hull.

Other passengers were winched to safety by helicopters.

Student Lim Hyung-min told broadcaster YTN after being rescued that he and other students jumped into the sea wearing life jackets and then swam to a nearby rescue boat.

"As the ferry was shaking and tilting, we all tripped and bumped into each another," Lim said, adding that some people were bleeding. Once he jumped, the ocean "was so cold. ... I was hurrying, thinking that I wanted to live."

Many of the passengers were children and their teachers from a high school in Seoul on a field trip to Jeju island, about 100 km south of the Korean Peninsula.

An official from Danwon High School in the Seoul suburb of Ansan said earlier that all of its 338 students and teachers had been rescued, but that could not be confirmed by the Coast Guard or other officials involved in the rescue.

Witnesses said many people were probably still inside the ferry, which officials said was carrying 150 vehicles.

It began to list badly about 20 km off the southwest coast as it headed for Jeju.

A crew member of a government ship involved in the rescue, who said he had spoken to members of the ferry's crew, said the area was free of reefs or rocks and the cause of the accident was probably some sort of malfunction on the vessel.

The ferry had left the port of Incheon, about 30 km west of Seoul, late on Tuesday.

It sent a distress signal early on Wednesday, the Coast Guard said, triggering a rescue that involved almost 100 Coast Guard and navy vessels and fishing boats, as well as 18 helicopters.

A US navy ship was at the scene to help, the US Seventh Fleet said, adding it was ready to offer more assistance.

Those rescued - wet, stunned and many without shoes - were taken to Jindo Island, where medical teams wrapped them in blankets and checked them for injuries before settling them down on the floor of a gymnasium.

Lee Gyeong-og, a vice- minister of the Public Administration and Security Ministry in the Republic of Korea, said 30 crew members, 325 high school students, 15 school teachers and 89 non-student passengers were aboard the ship.

The Maritime Ministry said the country's two previous deadliest ferry disasters were in 1970 when 323 people drowned and in 1993 when 292 people died.

Reuters-AP-Xinhua