The group rates Cambodia the 20th-most corrupt nation in the world, putting it in the company of Guinea, Kyrgyzstan and Yemen.
Hun Sen said claims on the South China Sea should remain a regional issue between “Asean and China only.”
Several Asean members, notably the Philippines and Vietnam, have overlapping claims to the sea with China and Taiwan.
China claims ownership of much of the South China Sea, along with four ASEAN states, including the Philippines.
Host President Hun Sen focused on economic issues in his opening remarks Tuesday.
Cambodia had left the contentious issue off the agenda, following a visit by Chinese President Hu Jiantao over the weekend.
The displaced at Phnom Bath say they are vulnerable to heavy winds and rainstorms, and they fear poisonous snakes and insects.
Burma’s political reform process has been a high-profile objective for the 10 member bloc of the Association of Southeast Asian Nations.
The future of project is unclear, and many families have already been moved from proposed railway improvement sites.
Cambodia has 2.3 million hectares of land under concessions, a new report by the rights group Adhoc says.
At least 12 Cambodians were reported dead in Malaysia in 2011, nine of them housemaids and three of them factory workers.