BANGKOK, Nov. 19 (Xinhua) -- The government will keep closely monitoring and evaluate the anti-government movement prior to making a decision if the Internal Security Act (ISA) should be invoked during a mass rally starting from Nov. 29, Prime Minister Abhisit Vejjajiva said Thursday.

    The anti-government group -- the United Front for Democracy against Dictatorship (UDD), also known as the red-shirted people, announced the group will hold the mass rally from Nov. 29 to Dec. 3.

    "The government will see reports about the UDD movement ahead of the rally days prior to making the decision about the ISA enforcement," Thai News Agency quoted Abhisit as saying.

    The UDD group can make the anti-government movement, however, they have to abide by the law, the prime minister said.

    Also, Abhisit said the government will ensure peace and security during the rally days in a bid to let the people celebrate the new year time happily.

    The rally purpose is to bring down the coalition government, while the UDD group expects at least one million UDD supporters will join the rally, the UDD group said earlier.

    The UDD group aims to overthrow the Democrat-led coalition government by ending 2009 as it could achieve its objective to topple the government since there is a corruption problem in several ministries, the group said.