A torpedo attack is among the ‘most likely’ causes of the sinking of a South Korean warship near the disputed border with North Korea, the defence minister has said amid rising tensions with Pyongyang.

‘A bubble jet caused by a heavy torpedo (attack) is thought to be one of the most likely things to be blamed, but various other possibilities are also under review,’ Defence Minister Kim Tae-Young said.

Shortly after the vessel sank on 26 March, Mr Kim said a mine or a torpedo could have been to blame, but Seoul subsequently rowed back and has since been careful to avoid pointing the finger at Pyongyang.

Several unidentified sources have been quoted in recent days as saying an underwater explosion was the cause of the sinking, but Mr Kim is the first minister to make the link explicitly since a probe into the sinking began.

Mr Kim's comments come as an international inspection team prepares to reveal its findings after the bow of the 1,200-tonne corvette was raised from the seabed, where it had been for a month.

Initial inspections of the stern, salvaged on 15 April, and the bow, which was raised on Saturday, indicate it was hit by the force of a blast, officials say.

Live local television footage of yesterday's salvage of the bow showed a hatch had come off its hinges and a chimney was missing.

‘This means underwater weaponry like a torpedo did not directly hit the vessel but exploded under the ship or at a very close range,’ an unidentified government official told Yonhap news agency today.

Pyongyang has accused the South's ‘war maniacs’ of seeking to shift the blame for the tragedy to the North.

The disputed Yellow Sea border was the scene of deadly naval clashes between the North and South in 1999 and 2002 and of a firefight last November that left a North Korean patrol boat in flames.

The communist North on Friday seized South Korean-owned assets at a mountain resort, warning that the two countries were on the brink of war over the sinking.

The tensions prompted US Secretary of State Hillary Clinton to say she hoped there would be ‘no miscalculation’ that could spark a new war between the Koreas.

South Korea President Lee Myung-Bak on Wednesday vowed a ‘resolute’ response to the Cheonan disaster, calling the worst peacetime loss of life for South Korea's navy a ‘wake-up call’ and describing the North as the world's ‘most belligerent’ state.

Ties between the two Koreas appeared to have entered a new phase of reconciliation after an historic inter-Korean summit in 2000 but have spiralled downwards since Lee's government took power in 2008.

Mr Lee has taken a tougher stance toward Pyongyang, while the North's nuclear weapons development sparked international condemnation and sanctions.

A high-ranking North Korean defector on Thursday said it was ‘obvious’ the communist regime's leader Kim Jong-Il was behind the sinking, accusing him of wanting to create chaos on the Korean peninsula.

Hwang Jang-Yop, the architect of the communist regime's ideology of ‘juche,’ or self-reliance, was once secretary of the ruling Workers' Party and a tutor to Mr Kim.