A North Korean submarine's torpedo¹ sank a South Korean navy ship on 26 March causing the loss of 46 sailors, an international report has found.

一项国际报道称，3月26日韩国一艘战舰沉没是朝鲜一艘潜艇的鱼雷导致，此次事故造成韩国46名海员丧生。

The Cheonan sinking has increased tensions between the two Koreas

Investigators² said they had discovered part of the torpedo（鱼雷，水雷） on the sea floor and it carried lettering（印字，刻字） that matched a North Korean design.

Pyongyang rejected the claim as a "fabrication（制造，装配） ", South Korea's Yonhap agency（联合通讯社） reported.

It said the North threatened war if sanctions were imposed by the South.

But South Korean President Lee Myung-bak pledged to take "stern action" against the North.

The White House described the sinking of the ship as an "act of aggression³" by North Korea that challenged peace.

The Cheonan went down near the disputed inter-Korean maritime⁴ border, raising tension between the two nations, which technically⁵ remain at war.

The shattered wreck⁶ of the 1,200-tonne gunboat（炮艇） was later winched（用绞盘拉） to the surface, in two pieces, for examination.

'Perfect match'

The investigation⁷ was led by experts from the US, Australia, Britain and Sweden.

It said: "The evidence points overwhelmingly（压倒性地） to the conclusion that the torpedo was fired by a North Korean submarine.

"There is no other plausible⁸（似合理的） explanation."

The report said the torpedo parts found "perfectly⁹ match" a torpedo type that the North manufactures.

Lettering found on one section matched that on a North Korean torpedo found by the South seven years ago.

There had earlier been a number of explanations suggested for the sinking, including an accidental collision with an unexploded sea mine left over from the Korean War.

Mr Lee's presidential office said he had told Australian Prime Minister Kevin Rudd: "We will be taking firm, responsive measures against the North, and through international cooperation, we have to make the North admit its wrongdoing and come back as a responsible member of the international community."

However, the BBC's John Sudworth in Seoul says agreeing an international response will be difficult as the diplomatic options will be limited.

Chinese Vice¹⁰ Foreign Minister Cui Tiankai said on Thursday the sinking of the vessel¹¹ was "unfortunate" but he would not comment on the international report.