Southeast Asian leaders have begun talks that are set to focus on territorial disputes, a declaration on human rights, economic cooperation and deadly ethnic unrest in Burma.

The annual Association of Southeast Asian Nations summit opened Sunday in the Cambodian capital of Phnom Penh, with leaders of the 10-nation ASEAN bloc expected to present a united front against China's territorial claims in the South China Sea. Beijing claims nearly all of the resource-rich region, against sovereign claims by Vietnam, the Philippines, Malaysia, Brunei and Taiwan.

The ASEAN leaders adopted a non-binding declaration Sunday they say will guarantee human rights protections for the population of the region. However, rights groups say the declaration contains loopholes that could allow authoritarian governments such at Vietnam and Laos to skirt the agreement.

Also high on the ASEAN summit agenda will be bloody violence between Burma's Rakhine Buddhists and Muslim Rohingya, which has displaced more than 22,000 people since June.

U.S. President Barack Obama will meet with ASEAN leaders in Cambodia Monday and Tuesday. He is expected to raise concerns about long-standing human-rights problems. The president is expected to urge Cambodian Prime Minister Hun Sen to hold free and fair elections and end land seizures.

The 10 ASEAN members are host Cambodia, along with Brunei, Laos, Indonesia, Burma, Malaysia, the Philippines, Singapore, Vietnam and Thailand.