The search for 46 missing marines continued in the waters near the disputed border between North and South Korea Saturday amid fading hope of finding survivors after an explosion caused a naval ship to sink.

Officials said military divers who entered the water Saturday were thwarted by fierce waves and high winds. Divers twice attempted to get to the wreckage. They were unsuccessful both times, Rear Adm. Lee Kisik of the Joint Chiefs of Staff told lawmakers.

The 1,200-ton Cheohan, with a crew of 104, had been on a routine patrol mission. Fifty-eight members of the crew have been rescued. Authorities say it is likely that the missing marines got trapped in the vessel, and hope of rescuing them is fading.

An explosion at the back of the ship shut down the engine and caused a power loss on Friday. The ship sank just over three hours later, Lee said.

There has been speculation that the ship hit a mine, but no official cause for the explosion has been determined.

Elliot Tepper, a South Asian studies specialist at Carleton University, said the only certainty is that there was a maritime tragedy.

"There was a report that the ship fired on something before it sank; now it's coming out that, no, it was a second ship, it was further south, and it was maybe a flock of birds," he told Â鶹´«Ã½ Channel Saturday. "There is confusion."

The families of the missing marines are angry about a lack of information about what happened, and some have protested at a South Korea naval base.

On Saturday, about 150 relatives of the missing marines pushed by security guards to confront military officials at the Pyeongtaek naval base. Some screamed "Liars!" and climbed onto the car of a rescued captain as he drove off.

A picture of a chaotic explosion and marines desperately trying to get off a sinking ship is emerging from the accounts of survivors and witnesses.

Staff Sgt. Shin Eun-chong, 24, told his relatives that he was on night duty when a huge boom echoed behind him and split the ship apart. The vessel began to tilt, and his glasses fell off his face as he fell to the deck, relatives at a Pyeongtaek naval base told The Associated Press.

"Yells and screams filled the air," Kim Jin-ho, a seaman who was on a local passenger ship bound for Baengnyeong, told cable news channel YTN. "Marines on deck were desperately shouting: 'Save me!"'

Military planes and boats searched the waters off the South Korean island of Baengnyeong, which lies just 17 kilometres from North Korea. Because the ship sank in waters that are part of the disputed maritime border between North and South Korea, there were initial fears that the explosion was caused by an attack.

There is no evidence tying North Korea to the explosion, and the cause of the sinking may not be revealed for some time.

"There was a sinking a few years ago and it took them 17 days to come up with an answer," Tepper said. "It would not surprise me if it turned out to be some kind of a mine that was an accidental hit. Those waters are mined; mines float."

The sinking of the Cheohan is one of South Korea's worst naval disasters. Local media reported that the country's worst maritime accident occurred in 1974, when a ship sank off the southeast coast in stormy weather, killing 159 sailors and coast guard personnel. In 1967, 39 sailors were killed by North Korean artillery.

The sinking comes after North Korea had threatened "unpredictable strikes" against South Korea and the U.S., after hearing a report that the two countries plan to prepare for possible instability in North Korea.

With files from The Associated Press