BANGKOK: Supporters of fugitive former Thai premier Thaksin Shinawatra vowed Wednesday to defy a government order banning them from an area of Bangkok where they plan to hold a mass rally this weekend.

The government said it would use a harsh internal security law to prevent the so-called "Red Shirt" demonstrators from gathering on Sunday afternoon at the Royal Plaza, their scheduled venue in the heart of the capital.

The protesters want current Prime Minister Abhisit Vejjajiva to dissolve parliament and call snap elections. Thaksin was toppled in a coup in 2006 and his allies were driven from government in December.

"No demonstration will be allowed in the area under the Internal Security Act," Deputy Prime Minister Suthep Thaugsuban told reporters, adding that it would also cover the cabinet and prime minister's offices at Government House.

His announcement came just a day after Abhisit said the protesters would be allowed to mass in the area, but that they would be subject to the security law which allows the military to take to the streets.

"Red Shirt" leader Veera Musikapong said the protesters would continue with their plans to gather at Royal Plaza, adding that they would meet in the afternoon and disperse by midnight.

"It will be a peaceful protest and will not last long, so the government should not be able to enforce the security act. It will deprive people of their freedom and human rights," Veera told reporters.

The protest group will also seek an emergency injunction from a court, he said.

Thailand's government is keen to prevent a repeat of the chaos in April when thousands of Red Shirts surrounded Government House and then went on a rampage through the capital, before caving in to threats of a military crackdown.

After keeping quiet for several months, supporters of the ousted Thaksin last week massed again at a parade ground in Bangkok to hand in a three-million-name petition seeking a royal pardon for their icon.

Billionaire Thaksin was toppled three years ago following protests by the rival, royalist "Yellow Shirt" movement. Last year he fled the country to avoid a two-year jail term for corruption.

The Yellow Shirts themselves surrounded Government House exactly a year ago to oppose the then-government, which was led by Thaksin's allies, leading to violent clashes with police.

That government collapsed in December after the Yellow Shirts blockaded Bangkok's main airports, bringing Abhisit to power and angering supporters of the exiled Thaksin.

Twice-elected Thaksin still enjoys huge support among Thailand's poor, particularly in rural northern parts of the country, but is hated by the Bangkok-based elite in the palace, military and establishment.