The Democratic People's Republic of Korea (DPRK) on Tuesday proposed a joint inspection group with the U.S. to investigate the sinking of the South Korean warship "Cheonan" in late March, the official KCNA news agency reported.

The DPRK put forward the proposal in the fourth round of the DPRK-U.S. colonel-level military working contact, the report said.

According to the KCNA, the contact, held in Panmunjom on Tuesday, was preparing for the DPRK-U.S. general-level talks.

The DPRK proposed a Korean People's Army (KPA)-U.S. joint inspection group to "probe into the truth behind the Cheonan case."

It suggested the heads of the joint inspection group from the two sides should be high-ranking general-level officers appointed by the KPA and U.S. forces.

The group, to be made up of 20 to 30 members from each side, might work for 3 to 5 days or "a necessary period if the inspection was extended."

The investigation would include the scene of the incident, the salvaged warship, witnesses, material evidence and relevant objects, the DPRK said in the proposal.

"All possible methods, including field investigation, analysis of material evidence, hearing from witnesses and analysis of data shall be employed to the maximum," the proposal said.

Meanwhile, the U.S. should "provide conveniences such as the provision of all the data requested by the KPA and guarantee of the overland passage and personal security of its members," the proposal said.

The KCNA news agency quoted the head of the DPRK side as saying that the proposal was "a fair, aboveboard and landmark one, understandable and acceptable to everyone in the light of its legal validity and realistic propriety."

The DPRK official stressed that whether or not the U.S. accepts the proposal will confirm its final stand on the clarification of the case.

According to the KCNA, the U.S. side insisted on its proposal for a "joint assessment group" in the contact and the both sides had agreed to hold the fifth round of the contact in Panmunjom, depending on their programs.

The 1,200-ton "Cheonan" with 104 crew members onboard sank on March 26 near the maritime border with the DPRK after an unexplained explosion. Only 58 sailors were rescued shortly after the sinking.

South Korean investigators issued the results of the investigation on May 20, saying that the "Cheonan" was sunk by a torpedo from the DPRK. The DPRK National Defense Commission issued a statement on the same day, rejecting the claim of South Korea and offering to send an inspection group to South Korea to verify material evidence. However, South Korea rejected the DPRK's request.