China said on Tuesday it was seriously deliberating on the joint investigation into the sinking of a Republic of Korea (ROK) warship and the responses of all parties.

"The sinking of Navy frigate 'Cheonan' is a complicated incident, and China doesn't have the first-hand information. China will objectively and fairly deal with the incident in accordance with the facts," said Foreign Ministry spokesman Qin Gang at a regular press briefing.

On March 26, the 1,200-ton Navy frigate "Cheonan," with 104 crew members onboard, went down off the ROK island of Baekryeong off the west coast due to an unexplained explosion. Forty-six sailors were killed.

Seoul said after completing an investigation that the warship was torpedoed by the Democratic People's Republic of Korea (DPRK). But Pyongyang has denied its involvement in the incident.

The ROK on June 4 formally referred the case to the United Nations Security Council.

Qin said the Security Council was discussing the issue, and held an unofficial dialogue. "The statements by the ROK and the DPRK on that occasion will help the member countries of the Security Council to learn the situation."

The 15-nation council on June 14 held two separate meetings with the ROK and the DPRK to discuss the sinking. Mexico's UN Ambassador Claude Heller, the council president this month, expressed grave concern over the incident after the close-door meetings.

Qin again urged all sides to maintain calm and restraint, so as to avoid escalation of the situation.

China would continue to strive for peace and stability on the Korean Peninsula, Qin said.

On a question concerning the 60th anniversary of the outbreak of the Korean War, Qin said all sides should take the history as a mirror and value the hard-won peace and stability. All sides concerned should make joint efforts in this regard especially at such a critical time.

China was a peace-loving country and it would develop friendly relations with countries in the region on the basis of the five principles of peaceful coexistence, and maintain peace and stability on the Korean Peninsula, he said.