Officials from member states of the Association of Southeast Asian Nations begin gathering in Singapore Saturday for ASEAN's annual summit conference. As VOA's Luis Ramirez reports from our Southeast Asia Bureau in Bangkok, the issue of Burma's threats to regional security will be high on the meeting's agenda.

On Tuesday, ASEAN will mark 40 since its establishment, with the signing of its new charter. The charter will put the grouping on track for setting up a free trade zone in the region by 2015.

Discussions during the five-day conference will focus on bringing down trade barriers and strengthening economic links with individual countries, and groupings such as the European Union.

There will also be talks on the environment, including common efforts toward reducing pollution, and increasing access for more people in the region to clean water.

Looming large on the political agenda is the matter of Burma, and the question of how ASEAN should deal with what many believe is a rising threat to regional security.

ASEAN's members are divided on how to approach Burma. Some, like Thailand, Vietnam, Laos and Cambodia, want to maintain the group's traditional approach of constructive engagement. Others, including Singapore, Indonesia, and the Philippines, are leaning toward more decisive action. That could include threatening Burma with expulsion from ASEAN unless it takes real steps toward democratic change and the protection of human rights.

ASEAN expressed revulsion at the Burmese military's violent crackdown on pro-democracy demonstrators in September. However, Roshan Jason, director of the ASEAN Inter-Parliamentary Myanmar Caucus, says some ASEAN members have continued to strengthen economic ties with the Burmese military leadership.

"On the one hand, you express revulsion, but on the other hand you're (helping) the pocket of the junta, which will just encourage them to buy arms to use against their own people," Jason said.

Critics accuse Thailand - Burma's biggest trading partner - of being the least willing to get tough, because of the billions of dollars in investments it has in the country. These include gas deals that provide Burma's generals with millions of dollars in revenues each month. Just this week, media reports quoted Thai officials as saying Thailand is considering developing an oil field in Burma in cooperation with China.

Zinn Linn is with the National Coalition Government of the Union of Burma, an activist group based in Thailand. He says he has no hope that Thailand will join in efforts to pressure Burma's ruling military council, the State Peace and Development Council, or SPDC.

"Thailand is not so interested in the problem of Burma," he said. "They're only interested in their benefits along the border. They are very afraid. [If] the SPDC closes the border points, it will hurt their border economy. The SPDC knows their weak points. So, Thailand, we cannot rely upon them."

A draft of the ASEAN charter to be signed Tuesday suggests the organization will remain committed to non-interference in the internal affairs of its members. Activists see that as a sign ASEAN will continue to refrain from putting meaningful pressure on the Burmese leadership.

The leaders of Cambodia and Laos are scheduled to be the first to arrive in Singapore on Saturday. Burma will be represented by its new Prime minister, Thein Sein, who is due to arrive Sunday.