US President George W Bush departed Bangkok Thursday for Beijing, where he plans to chide China for its human rights record and call on the communist country to help pressure Myanmar's military leaders.

Bush, on a two-day visit in Thailand, lunched with Myanmar dissidents before departing for the Chinese capital, where he is to attend Friday's opening ceremony of the Olympic Games.

"He is going to talk with China about Burma even though he seems to be worried that China's interests are different from the US's interest on Burma," said Win Min, one of nine Thailand-based Myanmar dissidents who lunched with Bush Thursday in Bangkok.

China is deemed the closest political ally of Myanmar, which was once called Burma, and one of the few world powers with any influence over the country's ruling junta.

The international community has long been calling on Myanmar's military regime to implement democratic reforms and free political prisoners, including opposition leader and Nobel Peace Prize winner Aung San Suu Kyi, who has been under house arrest for the past five years.

Bush and his wife, Laura, have championed the cause of Myanmar dissidents, helping to keep the country's struggle for democracy in the international limelight.

"We seek an end to tyranny in Burma," President Bush said in a major policy speech he delivered Thursday in Bangkok. "America reiterates our call on Burma's military junta to release Aung San Suu Kyi and all other political prisoners, and we will continue working until the people of Burma have the freedom they deserve."

Bush, who said his administration's policy of engagement with China had helped defuse potential security threats over such issues as the North Korean nuclear programme and tensions between China and Taiwan, expressed optimism about China's capacity for political change in the wake of its recent economic takeoff.

"Young people who grow up with the freedom to trade goods will ultimately demand the freedom to trade ideas, especially on an unrestricted internet," Bush said in his last major policy speech on US-Asian relations. "Change in China will arrive on its own terms and in keeping with its own history and traditions. Yet change will arrive."

Bush, whose presidency ends in January, claimed the United States' diplomatic engagement with Asia over the past seven years under his administration had helped bring in a period of economic prosperity and stability in Asia.

Its active, constructive engagement had also placed the United States in a good position to make criticisms where necessary, Bush said.

"America stands in firm opposition to China's detention of political dissidents, human rights advocates and religious activists," Bush said in addressing an audience of about 500 at the Queen Sirikit Convention Centre.

The Bushes used their Thailand visit to highlight the political situation in Myanmar, which has been under military dictatorships since 1962.

Laura Bush visited a refugee camp on the Thai-Myanmar border for Karens, one of several ethnic groups fighting Myanmar's junta, and a clinic run by a Karen doctor, Cynthia Maung.

President Bush stopped in Thailand in part to mark the two countries' 175th year of diplomatic relations, making Thailand the oldest US ally in the region. Prior to Thailand, he visited South Korea on his week long, three-nation Asia trip.