Premier Wen Jiabao, Republic of Korea President Lee Myung-bak (center) and Japanese Prime Minister Yukio Hatoyama (right) walk with elementary school students on Sunday as they arrive to plant a tree in Seogwipo, on the ROK's Jeju Island.[Ahn Young-Joon/Reuters]

There is an urgent need to defuse the fallout of the sinking of a Republic of Korea (ROK) warship, Premier Wen Jiabao said on Sunday, calling on leaders in the region to push for peace and avoid clashes.

Wen's remarks came at the end of a weekend trilateral summit, which was scheduled to focus on trade but was overshadowed by the sinking of the Cheonan in March.

"The most pressing task now is to appropriately deal with the grave impact of the Cheonan incident, gradually ease the tense situation and, especially, avoid clashes," Wen said at a joint press conference with ROK President Lee Myung-bak and Japanese Prime Minister Yukio Hatoyama.

He said China will continue to "actively communicate with relevant parties and lead the situation to help promote peace and stability in the region, which suits the three countries' common and long-term interests best".

"We should spare no efforts in maintaining peace and stability in Northeast Asia. Development will be out of the question without this prerequisite and hard-won achievements will be lost."

As the region faces many new challenges, the three countries should take into account each other's major concerns and properly handle sensitive issues to enhance mutual trust, Wen said.

Lee said the warship sinking poses an "important global challenge", which needs to be "properly dealt with".

"I expect very wise cooperation in dealing with this incident from both China and Japan as responsible countries," he added.

Hatoyama, whose country on Friday announced new sanctions against Pyongyang over the incident, said the three leaders agreed "that this is a serious issue related to peace and stability in Northeast Asia".

The DPRK has denied any involvement in the sinking. On Sunday, tens of thousands of people packed the main square in Pyongyang for a rally condemning the ROK and the US.

"Because of the South Korean (ROK) war-loving, mad puppets and American invaders, the North and South relationship is being driven to a catastrophe," Choi Yong-rim, secretary of the DPRK Workers Party, told the crowd in Pyongyang.

Tokyo and Seoul have been pressing Beijing to agree with the May 20 findings by a multinational investigation team that Pyongyang torpedoed the Cheonan, killing 46 sailors.

However, Beijing has not endorsed the findings, saying it attaches great importance to the international probe and reaction, and will take a position on the issue in an objective and fair manner.

Yonhap news cited an unnamed government official as saying the ROK government hopes to write a letter to the chairman of the United Nations Security Council as early as this week to set out its claims.

The report said the exact timing for taking the case to the UN has not been set yet as further discussions are needed with other nations.

The three leaders on Sunday also witnessed the signing of several agreements including a blueprint mapping out cooperation in the region over the next decade and the setting up of a secretarial office for the trilateral mechanism in Seoul.

Wen arrived in Tokyo after leaving the ROK on Sunday afternoon on the second leg of his four-nation Asian nation tour, which will also take him to Mongolia and Myanmar.