The Association of South-East Asian Nations (ASEAN) on Sunday rejected a call by the US Senate to suspend Myanmar following a violent crackdown on pro-democracy protests.

ASEAN Secretary General Ong Keng Yong said the US Senate resolution was not doable from the perspective of the 10-member regional bloc.

"Our approach is not to take such confrontational, drastic action, especially when it does not yield us any good results," he told reporters ahead of the ASEAN Leaders' Summit on Tuesday.

Ong urged the international community to build on the efforts of Ibrahim Gambari, the special envoy of the United Nations secretary general, who has been granted access of numerous personalities in visits to Myanmar.

"The challenge for ASEAN is to prevent a slippage of what Gambari has initiated," he said. "We believe that there should be intensified dialogue between ASEAN and the Myanmar leadership to stay focused on this diplomacy."

The US Senate on Friday unanimously adopted a resolution urging ASEAN leaders to suspend military-ruled Myanmar from the grouping for recent violent suppression of demonstrations.

At least 14 people were killed in September in Yangon City during the military crackdown on protests led by Buddhist monks.

Amnesty International estimated that 700 people were still in detention after being arrested during the protests.

In its resolution, the US Senate urged ASEAN to consider "appropriate disciplinary measures, including suspension, until such time as the government of Burma has demonstrated improved respect for and commitment to human rights."

Ong said isolating Myanmar, formerly called Burma, would not help resolve the problem.

"There's really no other option," he said. "The Myanmar guys are quite happy to be left alone. They are not afraid of being isolationists. They can just their door and go into hibernation."

He also urged international critics to stop telling ASEAN what to do.

"The rest of the world think they know what is good for all of us," he said. "But what we are saying is please allow us some democracy of ideas, democracy of option. You are advocating democracy but you are saying your ideas is the only workable idea."

Leaders of the Association of South-East Asian Nations (ASEAN) gathered in Singapore on Sunday ready to sign a landmark charter giving legal status to the 40-year-old body and making strides in human rights.

With Myanmar's Prime Minister Thein Sein and Foreign Minister U Nyan Win set to attend and the delegates from the 10-member bodies staying in 11 different hotels, police designated "protected areas" giving authorities greater leeway to deal with possible security threats, demonstrations or other incidents.

Among the affected venues and a 500-metre perimeter around each are The Shangri-La Hotel where the 40th anniversary summit is taking place, The Raffles City Convention Centre site of a gala dinner and the Asian Civilizations Museum where a reception will be held.

Nearly 1,000 delegates from 43 countries are attending. Their security is the focus of more than 2,000 police.

Philippines President Gloria Arroyo emphasized the importance of ASEAN.

The group is "becoming a more cohesive regional powerhouse that will enhance the interest of each member and provide balance to the rise of China as well as to our traditional relationships with North America and Europe," she said in a statement.

While the charter, a blueprint for an ASEAN economic community by 2015, and a document on climate change and the environment are highlights, diplomats said Myanmar is overshadowing the other issues after its bloody crackdown on pro-democracy protesters in September.

ASEAN countries have made many commitments over the years, but have only implemented a third of them, said Professor Tommy Koh, Singapore's representative on the task force which drafted the charter.

"This is not an acceptable record," Koh said. "A key feature in the charter is the emphasis on developing a culture of taking our obligations seriously," he added.

The secretary-general will be empowered to monitor compliance with ASEAN agreements and report breaches to the summit, he said.

Referring to critics who maintain that ASEAN is little more than a "talk shop," Koh said the charter will enable the grouping to play a bigger role in regional and global affairs.

ASEAN includes Singapore, Thailand, Malaysia, Indonesia, the Philippines, Brunei, Cambodia, Laos, Vietnam and Myanmar.

The UN Secretary General's special Adviser Ibrahim Gambari is scheduled to brief the East Asia Summit which includes the ASEAN countries in addition to China, India, Japan, South Korea, Australia and New Zealand.

Police have warned against staging any outdoor protests after learning of plans by foreign students to do so on Monday.

A petition was released however calling on the UN Security Council to bring "tangible results" in the national reconciliation and political reform process.

The document was signed by 3,626 people or 10 per cent of the Myanmar nationals in Singapore.

A group calling themselves the "Overseas Burma Patriots" said they wanted Singapore to give the petition to the council.

Public demonstrations against Myanmar's junta have flared elsewhere, but police said Singapore's prohibition against outdoor gatherings of more than four people without official approval is in full force.

ASEAN admitted Myanmar a decade ago despite opposition from the United States and the European Union over its human rights record and detention of pro-democracy leader Aung San Suu Kyi.

Critics maintain that keeping ASEAN's policy of non-interference in other members' affairs and continuation of decision-making by consensus could result in a "paper tiger."

While creating a human rights body, they point out the draft of the new charter lacks an effective enforcement mechanism.