HANOI, Vietnam — Putting China on notice, U.S. Secretary of State Hillary Rodham Clinton on Saturday said the United States has a key stake in increasingly tense territorial disputes between Beijing and its neighbors, as she assured nervous East Asian nations that the U.S. will remain a major power in the Asia-Pacific.

In a speech to East Asian leaders in Vietnam, Clinton declared that America has a direct national security interest in seeing peaceful resolutions to competing claims over islands that have led to a spike in animosity between China and other countries in the region, notably U.S. ally Japan.

Her comments were couched in diplomatic niceties, but the message was clear: China must not use its growing economic and military strength to bully its neighbors. Previous similar remarks from Clinton and other U.S. officials have drawn harsh criticism from the Chinese, who claim sovereignty over vast swaths of territory in the East and South China seas.

"The United States has a national interest in the freedom of navigation and unimpeded lawful commerce," Clinton told a meeting of the East Asia Summit in Hanoi. "And when disputes arise over maritime territory, we are committed to resolving them peacefully based on customary international law."

She praised China for taking some steps to engage with its neighbors about setting up a formal and binding code of conduct in dealing with the disputes, which extend to other strategic and potentially oil-rich islands in the region. But aides said her remarks were a signal to China that the U.S. is looking for far more.

Clinton arrived in Vietnam at the start of a two-week, seven-nation tour of the Asia-Pacific just as tensions between China and Japan over contested islands in the East China Sea — called Diaoyu in China and Senkaku in Japan — flared up, sending Sino-Japanese relations plummeting to a new low.

The dispute erupted last month after a Chinese fishing trawler collided with two Japanese patrol boats near the islands. The row that followed included protests, canceled meetings and Chinese restrictions on key metal exports that drew international concern, including from the United States.

The U.S. has appealed for the two countries to resolve the matter peacefully but has made clear it sides with Japan in the current imbroglio. After meeting with Japan's foreign minister in Hawaii on Wednesday, Clinton said the islands are covered by a U.S.-Japan mutual security pact, although Washington takes no position on their ultimate sovereignty.

That infuriated Beijing, which on Friday said it was "strongly dissatisfied" with her comments and lashed out at both the U.S. and Japan, accusing Tokyo of "ruining the atmosphere for leaders of the two countries" who were to meet in Hanoi.

Before delivering her remarks to the leaders, Clinton met with a tightlipped Chinese Foreign Minister Yang Jiechi on the sidelines of the summit but neither spoke to the matter at a brief photo session before journalists.

Later Saturday, Clinton is to make a brief stop on China's Hainan Island for talks with Chinese State Councilor Dai Bingguo at which the territorial disputes, China's policy on the export of rare earth minerals key to high-tech industries and an upcoming state visit of Chinese President Hu Jintao to the United States will be prime topics of discussion.

She will then travel to Cambodia, Malaysia, Papua New Guinea, New Zealand and Australia.

In her comments to the summit, Clinton said the U.S. had no intention of relinquishing its role as a dominant power in the Asia-Pacific, asserting that "we will continue to leverage the strength of our bilateral relationships (and) continue expanding our emerging partnerships with a wide range of countries."

She urged regional leaders to take prominent roles in dealing with threats from Iran and North Korea's nuclear programs, combatting climate change and helping to shore of the ailing global economy.

Clinton also called on East Asian leaders to work together to improve human rights conditions throughout the region. The U.S. has major human rights concerns in several countries represented at the summit, including China, Vietnam, Cambodia and Myanmar.

"We do believe that certain values are universal and that they are intrinsic to stable, peaceful and prosperous countries," she said. "Human rights are in everyone's interest." (AP)