Prominent activists from military-ruled Myanmar and Cambodia were barred Saturday from a meeting with Southeast Asian leaders, upstaging the opening of a summit billed as a historic step toward greater human rights in the region. The two activists were barred from a meeting on human rights in the region, after the leaders of Myanmar and Cambodia threatened to walk out if they attended. The activists had been selected by a regional human rights forum to act as delegates for their respective countries, along with activists from the other eight delegate nations. Two hours later, Thai Prime Minister Abhisit Vejjajiva officially opened the annual ASEAN summit with an address stressing that "ASEAN will put people first - in its vision, in its policies, and in its action plans." US Deputy Assistant Secretary of State Scot Marciel called the incident "unfortunate," and human rights advocates said it again proved Myanmar would continue to hamstring the Association of Southeast Asian Nations if it remained a member of the bloc.