WASHINGTON (Reuters) - The United States accused China on Tuesday of adopting a more aggressive military stance as a naval confrontation sparked anger in Beijing and raised tensions ahead of a U.S. visit by China's foreign minister.

The incident involving five Chinese ships and a U.S. Navy survey vessel threatened to complicate political and economic ties between the two powers as they wrestle with a joint response to the global economic crisis.

National Intelligence Director Dennis Blair told Congress the Chinese seem to be in a more military, aggressive posture, but it was still unclear whether Beijing was using its growing power for good or pushing people around.

The United States accused China of harassing the U.S. ship, the USNS Impeccable, in international waters off Hainan island, a launch-point of Beijing's military expansion and site of a major submarine base.

China countered that the United States distorted the truth and violated international and Chinese laws.

The U.S. claims are gravely in contravention of the facts and confuse black and white and they are totally unacceptable to China, Chinese Foreign Ministry spokesman Ma Zhaoxu said in Beijing.

The exchange came as Chinese Foreign Minister Yang Jiechi arrived in Washington to lay the groundwork for a meeting between Chinese President Hu Jintao and President Barack Obama at the G20 summit in London next month.

Yang has meetings planned on Wednesday with Secretary of State Hillary Clinton and Treasury Secretary Tim Geithner, and will visit the White House.

Blair called the incident in the South China Sea the most serious since a Chinese military plane collided with a U.S. electronic surveillance plane off Hainan in April 2001, during the early months of President George W. Bush's presidency.

A Chinese pilot was killed, and the U.S. plane made an emergency landing on the island. The U.S. crew was released 10 days later, and the plane was later returned.

EARLY MESSAGE?

The United States said the Chinese actions appeared deliberate, and some analysts said China might be sending a message early in the Obama administration about its rights to keep foreign navies from conducting surveillance near its economic zone.

The dispute comes as the two countries face a complex web of financial problems and the world's largest economies try to form a coordinated response to the growing global economic crisis.

A senior U.S. defense official on Tuesday said the United States would continue to operate in international waters, but he stopped short of saying any U.S. ocean surveillance vessels would return to the area where Sunday's incident occurred.

The director of the Defense Intelligence Agency, Lt. Gen. Michael Maples, told Congress that China was strengthening its ability to conduct military operations along its periphery and acquiring sophisticated air defenses from Russia.

It is building and fielding sophisticated weapon systems and testing new doctrines that it believes will allow it to prevail in regional conflicts and also counter traditional U.S. military advantages, he said.

The heightened tension over the naval confrontation coincided with some U.S. demonstrations to mark the 50th anniversary of the Chinese occupation of Tibet and the Dalai Lama's exile.

State Department spokesman Robert Wood said he would be surprised if the issue of Tibet was not raised during Ma's meeting with Clinton on Wednesday.

He said the United States wants to see a substantive dialogue between the Chinese government and representatives of the Dalai Lama.

You know, we're going to continue to raise this issue with the Chinese and do what we can to improve the situation on the ground, he said.

We remain concerned about the situation in Tibet, and we have been working hard to try to encourage an improvement of the situation for those who live in Tibet, Wood said.

(Editing by Cynthia Osterman)

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