MANILA, Philippines (AP) -- Southeast Asian countries want the world's leading nuclear powers to promise not to violate a treaty banning nuclear weapons in the region if they cannot formally accede to it, the countries said in a document.

Foreign ministers of the 10-member Association of Southeast Asian Nations will review the decade-old treaty to find ways of better enforcing it when they gather for an annual meeting in Manila next week.

Southeast Asia lies along the world's busiest sea lanes traversed by both civilian and foreign military vessels. The United States has a heavy military presence in the region but has traditionally refused to confirm or deny whether it transports nuclear weapons or stores them on its bases.

The possibility of nuclear weapons getting into the hands of terrorists has also been a concern.

"The emergence of possible non-state actors that might be eager to resort to the threat or use of nuclear weapons highlights the seriousness of this problem," Philippine Foreign Secretary Alberto Romulo said Friday.

While no violation of the Southeast Asia Nuclear Weapon-Free Zone treaty has been detected by ASEAN since the accord came into force in 1997, ASEAN has failed to convince key nuclear powers -- the United States, China, Great Britain, Russia and France -- to formally endorse it.

Under a five-year plan outlining steps to better ensure treaty compliance, ASEAN plans to ask those countries to at least promise to respect it.

Pending the nuclear powers' accession to the pact, ASEAN should "secure unilateral or collective declarations that they would not contribute to any activity that would violate the SEANWFZ treaty," according to the plan, a copy of which was seen by The Associated Press on Friday.

The plan, to be adopted by ASEAN foreign ministers in Manila next week, calls for more collaboration with the U.N. nuclear watchdog, the International Atomic Energy Agency, to improve the region's capability to detect any violation of the treaty.

It also seeks the establishment of a regional network for an early warning system for possible nuclear accidents and the development of a regional emergency preparedness and response plan.

A regional nuclear safety watchdog would be established under the plan to monitor ASEAN members pursuing nuclear energy programs. The plan encourages all ASEAN members to accede to international conventions on nuclear safety and those banning nuclear tests.

The treaty was signed in Bangkok on Dec. 15, 1995, and came into force two years later. Signatories agreed not to develop, manufacture or control nuclear weapons in the region and not to station, transport, use or test them.

The accord also bans the dumping at sea and on land and the discharge into the air of radioactive material or waste in the region. It allows the use of nuclear energy for peaceful purposes, particularly for economic development.

The United States has expressed reservations about the treaty because of possible restrictions on the passage of U.S. ships with nuclear weapons through the region's vital sea lanes.

U.S. warships presumed to be carrying nuclear weapons have frequently been the targets of protests in the region.

ASEAN's members -- Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Thailand, Singapore and Vietnam -- have all signed the treaty.