China is to face renewed pressure from South Korea to censure North Korea over the sinking of one of the South's warships, amid rising tensions.
Seoul is hosting a three-way summit with China and Japan as it steps up its diplomatic efforts over what it says was a torpedo attack by the North.
Beijing has so far refused to condemn North Korea, but has said it would assess the evidence objectively.
Pyongyang has fiercely denied the allegations.
South Korea says an investigation involving international teams uncovered indisputable evidence that North Korea fired a torpedo at the ship.
It has announced a package of measures, including a halt to most trade with North Korea, and is also seeking action via the United Nations Security Council.
If such action is to succeed, China's support is crucial.
Chinese Premier Wen Jiabao has already held bilateral discussions with South Korean President Lee Myung-bak.
Speaking on Friday, Mr Wen said China "will not protect" whoever sank the warship.
Beijing is under pressure to take a strong stance against North Korea but so far has not accepted the findings of the independent investigation.
Mr Wen said that China would take its position after "objectively and fairly judging" the evidence while "respecting the international probe and responses to it by each nation".
Early on Saturday, on his way to the summit, Japanese Prime Minister Yukio Hatoyama paid his respects at the graves of the 46 sailors who were killed in the explosion.
The BBC's John Sudworth in Seoul says the gesture was a demonstration of solidarity with South Korea and its conclusion that the ship was attacked by North Korea.
Japan has already said it is tightening its stringent sanctions against North Korea.
The three leaders will hold two days of talks on the South Korean resort island of Jeju.
North and South Korea are technically still at war after the Korean conflict ended without a peace treaty in 1953.