The meeting between Mr. Obama and leaders of the 10-member Association of Southeast Asian Nations will take place on the sidelines of the annual summit meeting of the Asia-Pacific Economic Cooperation forum in Singapore, the U.S. ambassador for Asean affairs, Scot Marciel, said Saturday.

Prime Minister Thein Sein of Myanmar will attend the meeting, which marks the 32nd anniversary of Washington’s relations with Asean, said a senior Myanmar diplomat, Min Lwin. The junta chief, Senior Gen. Than Shwe, typically shuns official meetings outside the country.

The talks would be the highest-level contact between Myanmar and the United States in decades.

Officials have not said whether Mr. Obama will meet privately with Thein Sein.