Parliamentary opposition leader Lim Kit Siang today criticised Thai Prime Minister Thaksin Shinawatra for threatening to walk out of next week's Asean summit if leaders raise the violent deaths of 87 Muslim protesters in the kingdom's insurgency-hit south.

Thaksin's threat was "most unbecoming of a Thai premier and Asean leader," said the DAP's veteran leader Lim in a statement.

The move could "only undermine the bid by the Thai government for its Foreign Minister, Surakiart Sathirathai, to succeed Kofi Annan as United Nations Secretary-General," Lim said.

He pointed out that Surakiart did not walk out of a meeting with US Secretary of State Colin Powell at an Asia-Pacific summit in Santiago last week when Powell raised the issue, but instead explained the Thai government's position.

"Why should Thaksin now threaten to walk out of the Asean summit if leaders from other Asean countries raise the issue of the continuing unrest, violence and bloodshed involving Muslims and Buddhists at the Vientiane Asean summit?"

The death of the 87 Muslim protesters on Oct 25 at Tak Bai near the border with Malaysia, mostly through suffocation after being piled into army trucks, has inflamed Muslim opinion in Thailand and elsewhere.

Behind-the-scenes talks

"If the topic is raised, I will fly back home," Thaksin told reporters ahead of the Nov 29-30 meeting of the Associaition of Southeast Asian Nations (Asean) in Laos.

"To interfere in internal affairs at a multilateral meeting is not the right thing to do and the chairman should not let it happen."

The killings - which prompted a spate of retaliatory attacks on Buddhists in the region - are not on the agenda but analysts said they expected them to feature in behind-the-scenes talks.

At least 550 people have died in Thailand's mainly Muslim south since a decades-old separatist insurgency sparked back into life in January.