US Secretary of State Hillary Clinton said on Saturday that maritime rows should be settled by international law, remarks likely to rile China, which wants to handle them directly with its neighbours.
Clinton waded into the dispute over South China Sea and East China Sea islands as she took part in the 16-nation East Asia Summit, which the United States is attending for the first time along with Russia.
"The United States has a national interest in the freedom of navigation and unimpeded lawful commerce," the chief US diplomat said in a speech to the EAS, repeating a US stand in the presence of China here in Vietnam's capital.
"And when disputes arise over maritime territory, we are committed to resolving them peacefully based on customary international law," Clinton said.
But she also sounded a softer note, saying "with regard to the South China Sea, we are encouraged by China's recent steps to enter discussions with ASEAN about a more formal binding code of conduct."
The Philippines said China on Friday made such assurances in response to concerns from leaders of the 10-member Association of Southeast Asian Nations (ASEAN) who met with China's premier Wen Jiabao on Friday.
ASEAN, which is part of EAS, hopes that a "declaration" on a mooted code of conduct could lead to a mechanism to govern actions in the disputed waterway -- a resource-rich region which is a vital conduit for trade in goods and energy.
Diplomatic sources say that a working group from ASEAN and China will meet in December to prepare the groundwork and establish technical details on how a code of conduct could be formulated.
The United States has said it is willing to help craft the legally binding mechanism to end a dispute that threatens regional stability.
However, diplomats say a major stumbling block to such a mechanism is Beijing's reluctance to deal with ASEAN collectively on the issue.
Beijing instead wants the matter discussed bilaterally with the group's members which have territorial claims -- a forum where it has more clout -- while ASEAN wants to speak as a group.
China has warned the United States against making the South China Sea dispute an international issue and rejected any form of interference from Washington.
To the north, a dispute still simmers between China and Japan after Tokyo on September 8 arrested a Chinese trawler captain near Japanese-administered islands, known as Senkaku in Japan and Diaoyu in China.
China was angered after Clinton, during talks in Hawaii on Wednesday with Japanese Foreign Minister Seiji Maehara, said the islands fall under chapter five of the 1960 US-Japan Treaty of Mutual Cooperation and Security.
Under the treaty, the United States is obliged to defend Japan against any attack on a territory under Tokyo's