Thailand's Cabinet on Tuesday approved the use of a special security law ahead of a rally to mark the third anniversary of a coup that ousted former Prime Minister Thaksin Shinawatra. Saturday's anti-government protest in Bangkok is expected to be the largest since demonstrations outside Government House in April turned into riots that left two dead and more than 120 injured. Invoking the Internal Security Act allows the country's internal security and counterinsurgency agency headed by Prime Minister Abhisit Vejjajiva to order curfews and restrict freedom of movement in situations deemed harmful to national security. 'We want to make sure we have the means to resolve the matter quickly if necessary,' said government spokesman Supachai Jaisamuth, who said the Cabinet approved the use of the act for five days, starting Friday. The law will cover the Dusit district of the capital where several traditional protest venues are located, including Parliament and the prime minister's office. The protesters plan to rally Saturday at nearby Royal Plaza, about half a mile (1 kilometer) from the home of the king's top adviser, whom protesters accuse of orchestrating the Sept. 19, 2006, coup that toppled Thaksin. 'We will gather at the square, and we believe the crowd size will be large enough that it will spill over to his house,' said protest leader Jatuporn Phromphan. 'Our leader was toppled by force. It has been three years and we want them to know what the people want.' Protest leaders have called off rallies in recent weeks after the government invoked the act, but vowed to go ahead with Saturday's demonstration. The act was also invoked during a regional security forum in July amid fear of protests. Even three years after his ouster, Thaksin remains at the center of Thailand's protracted political crisis. He was accused of corruption and abuse of power during his time in office, and was sentenced in absentia last year to two years in prison on violation of a conflict of interest law. However, the fugitive former leader remains popular among the urban and rural poor. Elections after his ouster brought his allies back to power, setting off months of protests that eventually shut down the capital's airports for a week. Court decisions then disqualified a pro-Thaksin prime minister for electoral fraud, and Abhisit formed the current coalition government. This weekend's protesters want Abhisit to dissolve Parliament and call new elections. The protest comes a day before Abhisit is due to leave for New York for the United Nations General Assembly. The protesters have also called for the resignation of Prem Tinsulanonda, an 88-year-old adviser to Thailand's revered king, and accuse the country's elite -- the military, judiciary and other unelected officials -- of undermining democracy by interfering in politics. The protesters have vowed they will disperse peacefully by midnight, but the government said invoking the security law was necessary amid fears the gathering could plunge Thailand back into turmoil. 