China offered no indication Thursday of plans to join the U.S. and its allies in blaming North Korea in the sinking of a South Korean warship, saying the issue remained «extremely complicated.» U.S. officials said Wednesday that China, a key North Korean ally, had indicated it is prepared to hold Pyongyang accountable for the March 26 torpedo attack and could join in some kind of formal rebuke by the U.N. Security Council, according to AP. However, when asked about the investigation into the incident, Chinese Foreign Ministry spokesman Ma Zhaoxu merely repeated an earlier Chinese statement that fell short of assigning blame. «The issue is highly complicated. China does not have firsthand information. We are looking at the information from all sides in a prudent manner,» Ma told reporters at a regularly scheduled news conference. «China's position on the ship remains unchanged,» he added. The sinking of the corvette Cheonan, in which 46 sailors died, has put Beijing in an uncomfortable position, forcing it to choose between traditional communist ally North Korea and close trading partner South Korea. Doing nothing would preserve relations with a loyal buffer state reviled by the world but could do major harm to China's aspirations to be seen as a responsible rising global power. While China appears to be seeking to buy time, tension on the divided peninsula has been rising dramatically since a team of international investigators said last week that a torpedo fired by a North Korean submarine tore apart and sank the ship. North Korea has denied involvement in the sinking and warned any retaliation would mean war. The incident will likely dominate a weekend trilateral summit in South Korea involving Chinese Premier Wen Jiabao and his South Korean and Japanese counterparts. U.S. officials said they expect Wen to hint that China will accept the results of the international investigation blaming North Korea. They said Wen is also expected to leave open the possibility of backing measures against Pyongyang at the U.N. Security Council, where China's veto could block even the mere discussion of the sinking. Other countries are also looking for action from China, with the Philippines' president-apparent urging Beijing on Thursday to use its influence on North Korea to defuse the tensions. «I did make the request that they would be, as our neighbors, in the best position to influence, with the end point of defusing tensions in the Korean Peninsula,» opposition Sen. Benigno Aquino III told reporters Thursday after meeting Chinese Ambassador Liu Jianchao. Aquino is leading by a landslide in votes cast in the May 10 election and is expected to be sworn into office on June 30.