The Democratic People's Republic of Korea (DPRK) has rejected South Korea's claim that Pyongyang was responsible for warship Cheonan's sinking, saying it will send a verification team to Seoul.

The DPRK has rejected the claim that its torpedo released by a submarine sank the South Korean warship in March. The country's National Defense Commission said it will dispatch inspectors to South Korea to verify the claim announced by a multinational team of investigators.

The investigators concluded early Thursday that the South Korean navy warship was torpedoed by a DPRK submarine and the torpedo was manufactured in the DPRK.

The group of civilian and military experts said the 1,200-ton warship Cheonan went sunk as a result of an "external underwater explosion" caused by a torpedo fired by a DPRK submarine, resulting in one of the worst peacetime casualties in the country's naval history.

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

The statement said the joint civilian-military investigation group (JIG) assessed that "a strong underwater explosion generated by the detonation of a homing torpedo below and to the left of the gas turbine room" caused Cheonan to split apart and sink.

The statement said, the propulsion parts, including propulsion motor with propellers and a steering section that have been collected from the site of the sinking, matched in size and shape with the specifications on the drawing presented in introductory materials provided to foreign countries by the DPRK for export purposes.

The marking in Hangul (Korean words), which reads "1 ben," or No.1 in English, found inside the end of the propulsion section, is consistent with the marking of a previously obtained the DPRK torpedo, it said, adding that this evidence allowed the JIG to confirm that the recovered parts were made in the DPRK.

President Lee Myung-bak has vowed to take "firm measure" against the DPRK over the sinking of its warship.

"(We) will take firm measures against North Korea and make it admit its wrongdoings through strong international cooperation," Lee told Australian Prime Minister Kevin Rudd in phone talks.

The DPRK has denied its involvement in the accident in April.

On Wednesday, DPRK's Committee for the Peaceful Reunification of Korea released a statement accusing South Korea of taking advantage of the sinking of its warship to push north-south relations to a catastrophe.

In the statement, the committee said the campaign against the DPRK launched by South Korea after the accident reached the height of its confrontation and war moves.