SEOUL -- South Korea declared Thursday that North Korea deliberately sank a South Korean warship two months ago, as investigators revealed major sections of a North Korean torpedo found last week near the site of the sinking.

The investigators said the torpedo parts match the design of one that North Korea advertises and exports to overseas customers. Some of the parts also match those in a North Korean torpedo that South Korea recovered several years ago.

"The evidence points overwhelmingly to the conclusion that the torpedo was fired by a North Korean submarine," the investigators said in a statement. "There is no other plausible explanation."

A dredge ship found many of the torpedo parts last Friday, including propellers, its propulsion motor and steering section. A marking inside the propulsion system reads "No. 1" in Korean lettering and, investigators said, is consistent with markings in a North Korean torpedo that the South Korean military obtained several years ago.

The investigators said that surveillance photography showed that several small North Korean submarines and a support ship were gone from their base for about five days around March 26. South Korea said it confirmed with neighboring countries, including China, that their submarines were at their home bases on March 26