China faces regional pressure at a summit on Sunday when South Korea and Japan will want signs that Beijing will accept UN censure of North Korea, blamed for sinking a naval ship.
Seoul and Tokyo are convinced that North Korea, whose reclusive leader Kim Jong-il visited China earlier this month, torpedoed the corvette Cheonan in March, killing 46 South Korean sailors, but Beijing has remained noncommittal.
Beijing's efforts to balance ties with its big trade partner South Korea with its support for North Korea have made for awkward diplomacy for visiting Chinese Premier Wen Jiabao, and that will continue at talks on Sunday likely to focus on the ship sinking and other security worries.
"Of course, the Cheonan incident will be discussed," Japanese Prime Minister Yukio Hatoyama told reporters before the talks with Wen and South Korean President President Lee Myung-bak.
"In this international environment, I would like to make efforts along with China to be able to take tough action."
The leaders of the three big northeast Asian powers have been meeting in Seogwipo, a honeymoon resort on the South Korean island of Jeju, for a weekend summit that was meant to boost plans for greater regional cooperation and economic integration.
Instead, the quarrel between North and South Korea has stolen the limelight.
The mounting antagonism between the two Koreas has unnerved investors, worried the confrontation could erupt into conflict in a region that is home to the world's second- and third-biggest economies -- Japan and China.
At the first session on Saturday, Hatoyama repeated calls to China to act on what Tokyo and Washington have said was convincing evidence of the North's wrongdoing.
China counts neighbouring North Korea as a friend and a buffer against the other, U.S.-allied neighbours. It has steered clear of condemning Pyongyang, saying it needs to consider the evidence and urging restraint on all sides.
Wen held to that position in a meeting with Lee on Friday, but he also said Beijing would protect nobody found responsible for the sinking, comments which gave some help to Lee who had been hoping the Chinese premier offer more forthright support.
"Premier Wen will face tremendous pressure from the Republic of Korea and Japan during these two days. But it's unlikely that he will make any major commitments," wrote Stephanie Kleine-Ahlbrandt, the North East Asia Project Director for the International Crisis Group, a non-government advisory organisation, in an emailed response to questions.
"With regard to the Cheonan, China seems confident that tensions will eventually diminish."
Hatoyama has pledged full support for Seoul and said Japan will back Seoul when it takes the North to the UN Security Council, seeking condemnation of the sinking. But Pyongyang may not bow even if China goes along with such steps, said Kleine-Ahlbrandt.
"We have seen plenty of cases in which external pressure has not worked on North Korea," she wrote. "It is therefore questionable whether further measures will have the desired effect in this situation."
North Korea has warned of war on the Korean peninsula if Seoul imposes sanctions, calling the South Korean government "military gangsters, seized by fever for a war".