Bangkok - Thousands of supporters of the People's Alliance for Democracy (PAD) marched on the Thai Parliament Monday from Government House, which they have held hostage since August 26.

PAD leaders said they would lay siege to parliament to block a new move to amend the constitution, expected to be initiated this week when a new cabinet under recently appointed Prime Minister Somchai Wongsawat is scheduled to announce its policies.

The PAD is a loose coalition of groups opposed to the return to power of former premier Thaksin Shinawatra, who was ousted by a military coup on September 19, 2006.

The current government is led by the People Power Party (PPP), a party with close ties to Thaksin that is now led by Somchai, Thaksin's brother in law.

There are fears among the PAD that this government is seeking to reinstate the 1997 constitution, a liberal, pro-political parties charter that paved the way for Thaksin's rise to power in 2001 to 2006 and allowed his Thai Rak Thai party to dominate the political scene unhampered by independent bodies and checks and balances.

A previous attempt by former premier Samak Sundaravej to amend the 2007 constitution, which favours the bureaucracy and has strengthened the judiciary and other checks on corrupt politicians, brought the PAD to the streets in May this year.

Samak lost his post last month when the Constituion Court found him guilty of moonlighting on the premiership for hosting television cooking shows.

The PAD protests culminated in the seizure of Government House on August 26. They have occupied the seat of administration since.

The arrest of PAD leader Chamlong Srimuang on treason charges Sunday was deemed an invitation to escalate the PAD protest and the derailing of efforts to reach a compromise with the movement that is fighting for an era of "new politics" in Thailand. (dpa)