Tokyo - US President Barack Obama Saturday called for Myanmar to release opposition leader Aung San Suu Kyi, saying it was a precondition for any softening of sanctions against the country's military junta.

Using the traditional name of the country, Obama said Burma needed to take "clear steps" toward democracy, including the unconditional release of all political prisoners, an end to conflicts with minority groups and a "genuine dialogue" with the opposition and minorities on a "shared vision for the future."

He noted that the US had begun communicating directly with the Burmese leadership after neither sanctions nor engagement by others had succeeded. The message Washington was sending via the newly opened lines was "that existing sanctions will remain until there are concrete steps toward democratic reform."

Obama was speaking to Japanese citizens, scientists and business people at Suntory Hall in Tokyo, a day after meeting with Japanese Prime Minister Yukio Hatoyama as part of his seven-day tour of Asia.

Also in his speech, Obama called for North Korea to return to denuclearization talks, urging it to choose "international integration" over "isolation that has compounded the horrific repression of its own people."

Obama repeated past assurances from Washington that the US was prepared to offer North Korea a "different future" of economic opportunity, with trade, investment and tourism giving the people of the impoverished Stalinist state a "chance at a better life."

In his speech, Obama also saluted China for its growing role and responsibility on the world stage, saying the US was seeking "pragmatic cooperation" with Beijing.

At the same time, he sought to calm worries that Washington's "deeper relationships with China" meant a "weakening of our bilateral alliances" in the Asia-Pacific region.

Obama declared Washington's intent to renew its active role in the Asian region after being "disengaged" in recent years, an apparent reference to his predecessor George W Bush's distrust of international organizations.

Obama is to meet Tuesday and Wednesday with Chinese President Hu Jintao in Beijing.

Later Saturday, Obama will meet with Japan's emperor and empress before departing for Singapore, where he will meet with the 10 leaders of the Association of South-East Asian Nations (ASEAN) on Sunday and participate in the annual summit of the Asia-Pacific Economic Cooperation (APEC) forum.

He plans to meet on the sidelines with Russian President Dmitry Medvedev in Singapore. (dpa)