By Jon Herkovitz
SEOUL (Reuters) - The likelihood North Korea sank a South Korean naval ship near their disputed border rose when Seoul said on Friday an external explosion probably caused the ship to split in two, killing dozens.
South Korea's defense minister said this month the 1,200-tonne Cheonan may have been hit by a torpedo, immediately putting suspicion on North Korea and stoking concerns that the incident could start a conflict on the long divided peninsula.
"Conclusively, after a visual inspection, there is a higher chance of an outer explosion than an internal one," Yoon Duk-yong, a top investigation official, told a news conference.
Local media is increasingly pinning the blame on North Korea, in the absence of any other likely reasons for the explosion which sank the corvette late last month, thought to have killed 46 sailors.
Yoon said the twisting of metal from the salvaged stern that was raised on Thursday indicated the blast had come from outside but the team will wait until the rest of the ship was raised and other evidence gathered before reaching a final conclusion.
"The Cheonan was also halved in the middle. Therefore, it is highly likely that a torpedo fired from a submarine or mine
destroyed the ship," military expert and former submarine
captain Jung Sung wrote in the JoongAng Ilbo daily.
The threat of triggering a major conflict, and so hurting its own rapid economic recovery, means South Korea is unlikely to take military action against the North if it does turn out to have deliberately sunk the ship, analysts said.
Relations between the two have already turned frosty since President Lee Myung-bak came to power in Seoul over two years ago, angering Pyongyang by ending the financial largesse that had for years been a lifeline for the broken North Korean economy.
In a fit of pique, the North this week froze assets of a South Korean firm at a joint tourism project north of the border once hailed as a symbol of cooperation.
The North has made no public mention of the ship sinking.
Uncertainty over North Korea's behavior and the health of its iron leader have become a major risk for the South.
Ratings agency Standard & Poor's said on Thursday it did not plan to raise the South's sovereign rating -- which would normally make it cheaper for South Korean borrowers overseas -- while risks involving Pyongyang's leadership persist.
Thirty-six of the 46 sailors who went missing were recovered from the ship's stern, the defense ministry said. The bodies of two other sailors were found before the salvage operation, and 58 were rescued alive.
South Korea expects to raise the front part of the ship in the next few days as it searches for clues to one if its deadliest naval disasters since the 1950-53 Korean war ended in a cease fire.
The sinking could also complicate the resumption of stalled international talks on ending North Korea's atomic arms program in return for aid to prop up its broken economy, experts said.
(Additional reporting by Christine Kim, editing by Jonathan Thatcher and Sugita Katyal)