SEOGWIPO, South Korea - Pressure was rising on regional giant China to support efforts to punish North Korea over the sinking of a South Korean warship - the issue that was dominating a three-nation weekend summit.

China showed no signs publicly Saturday of joining South Korea and Japan in rebuking Pyongyang, but Premier Wen Jiabao said he hoped their summit would help achieve peace. Officials said that Saturday's discussions focused on trade issues and that the ship sinking was on Sunday's agenda for the meeting on the South Korean resort island of Jeju.

As the main ally of reclusive North Korea, China has long been reluctant to back harsh measures against the state that shares its border and communist ideology. Its statements on the sinking so far have stressed caution and objectivity in the investigation, while also showing sensitivity to South Korean anger at the attack and at its own reluctance to endorse the investigation results or criticize Pyongyang.

But senior U.S. officials speaking on condition of anonymity after recent strategic talks in Beijing have predicted China will gradually endorse the view that North Korea should be held accountable.

An international investigation concluded that a North Korean torpedo struck and sank the Cheonan in March, killing 46 sailors in the South's worst military loss since the Korean War.

North Korea has repeatedly denied responsibility, and the state-run Korean Central News Agency said Saturday that the ship investigation was "a hideous charade" carried out by Seoul and its allies the United States, Australia, and Britain.

South Korea on Monday laid out a series of punitive measures and pledged to haul Pyongyang before the U.N. Security Council. The steps include slashing trade, resuming anti-North Korean propaganda broadcasts across the border, and launching large-scale naval exercises off the western coast.

The North has said the South's moves are pushing the peninsula closer to war.

"These anti-North Korean confrontations are an open declaration of war against us and an extraordinarily criminal act that pushes inter-Korean relations into a state of war," North Korean Maj. Gen. Pak Rim Su said Friday, according to broadcaster APTN. He spoke at a rare news conference of the National Defense Commission, which is headed by leader Kim Jong Il.

China wields veto power as a permanent Security Council member, so its support would be key to any bid to condemn or sanction North Korea in the United Nations.

Before the two-day summit began Saturday, Wen offered condolences to the families of the dead sailors at a meeting with South Korean Prime Minister Chung Un-chan.

"China is a responsible nation which insists on justice and is seriously considering the findings of the multinational investigation," Wen said, according to Chung spokesman Kim Chang Young. "China has maintained consistent views on the stability of peace on the Korean peninsula and opposes acts that destroy it," he quoted Wen as saying.

South Korean President Lee Myung Bak has pledged to take the North to the Security Council, and Japan has backed the move. Japanese Prime Minister Yukio Hatoyama's government on Friday instituted new sanctions against North Korea.