Bangkok  - The Thai cabinet on Tuesday agreed to impose the draconian Internal Security Act over the weekend to ensure law and order during a demonstration planned to mark the third anniversary of the September 19, 2006 coup.

The Internal Security Act will be enforced in the Dusit district of Bangkok from September 18-22, allowing authorities to arrest and crack down on protestors with impunity.

The United Front for Democracy against Dictatorship (UDD), as the backers of fugitive former prime minister Thaksin Shinawatra call themselves, plans to hold a mass rally at Bangkok's Royal Grounds on Saturday to mark the coup that toppled him.

They also plan to march to the house of royal Privy Council chairman General Prem Tinsulanonda over the weekend to protest his alleged role in supporting the the coup.

Prem, who was Thai prime minister between 1980-88, has a house in the Dusit district of Bangkok.

Current Prime Minister Abhisit Vejjajiva pushed for a cabinet decision to invoke the Internal Security Act to prevent a possible outbreak of violent protests in the capital.

"I am confident that most people in the country want peace to be maintained," Abhisit told The Nation newspaper. "Those who have different political views can express themselves by lawful means. If they exceed legal limits, law enforcers will have to step in."

Abhisit will travel to New York September 20-26 to attend the United Nations General Assembly and Group of 20 meetings. Deputy Prime Minister Suthep Thaugsuban will be left in charge of security during his absence.

Recent opinion surveys have shown that Bangkok denizens are fed up with street protests.

On April 11-12, UDD protestors stormed the venue of a summit of Asian leaders Thailand was hosting in Pattaya, 100 kilometre east of Bangkok, forcing Abhisit to cancel the event.

On April 13 they went on a rampage in Bangkok, burning buses and starting street riots, prompting an army crackdown on the movement which is seeking to bring down the Abhisit government and return Thaksin to power.

Thai society remains deeply divided by the Thaksin legacy. Between 2001-06, his government introduced populist polices that gave a sense of empowerment to Thailand's long neglected rural and urban poor.

The coup that ousted him was seen by the UDD supporters as a return to the status quo, bringing Thailand's Bangkok-based political elite back to power after Thaksin threatened them.

The past three years have been marred by a failure of the political system to bridge the divide between supporters of Thaksin and backers of the status quo, leading to unprecedented street protests that culminated with the seizure of Bangkok's two airports for a week in late 2008, and April's street mayhem.

Despite the seemingly endless Bangkok protests, very few have died in the demonstrations which have been largely non-violent. (dpa)