Burma and Cambodia blocked leading activists from attending talks with Southeast Asian leaders Saturday in Thailand, where the regional bloc is trying to promote human rights as part of its charter.
Leaders from the 10-member Association of Southeast Asian Nations - ASEAN - were set to hold rare talks with civil society representatives at their annual summit, taking place in the Thai beach resort of Hua Hin.
But, Burmese Prime Minister Thein Sein and his Cambodian counterpart Hun Sen said they would not take part if activists from their own countries were present.
Debbie Stothard, a coordinator with the Alternative ASEAN Network on Burma, said rights groups had no choice but the withdraw their Burmese and Cambodian representatives.
The barred activists were Khin Omar, a democracy campaigner from Burma, and Pen Somony, a volunteer coordinator from Cambodia.
Human rights have been a recurring issue for ASEAN, which has a charter that prevents interference in its members' affairs.
Soe Aung, with the Burmese rights group, told reporters that ASEAN needs to change its policy of non-interference or no change will ever come to Burma.
ASEAN comprises Thailand, Cambodia, Burma, Indonesia, Singapore, Malaysia, Vietnam, Laos, Brunei and the Philippines.