BANGKOK (AFP) - Five parties from Thailands shaky coalition government will push ahead with plans to amend the Constitution without the support of the Prime Ministers leading Democrat party, a minister said Monday. Though the changes are not expected to get parliamentary approval without backing from the Democrats and the leading Opposition party, the move is likely to destabilise further the already fragile six-party coalition. The five parties have agreed to submit to parliament on Wednesday (today) their plans for two changes to the 2007 Constitution, which was forced through by the then military government, said Tourism and Sport Minister Chumpol Silpa-archa. The Thai stock market fell last week on news that the Democrat party, led by Prime Minister Abhisit Vejjajiva, would not support the plans, fuelling speculation of a house dissolution. The country also faces intensifying political divisions outside parliament, with anti-government street protesters loyal to ousted former premier Thaksin Shinawatra promising fresh mass rallies later this month. Meanwhile, a suspected anti-government protester threw bags of human excrement into PM Abhisit Vejjajivas home in the latest sign of growing political tensions, his deputy said Tuesday. Deputy Premier Suthep Thaugsuban was quick to blame Mondays attack on Red Shirts - supporters of ousted former premier Thaksin Shinawatra who have announced plans to step up anti-government rallies in the coming weeks. Based on an assessment of the situation I believe that its the work of Red Shirt people. I learned about the incident yesterday and have instructed police to step up security around important people, Suthep told reporters. Police confirmed several plastic bags containing human excrement were thrown over a wall into the Prime Ministers residential compound on an upmarket street in central Bangkok. Abhisit said Tuesday his family were not shaken by the incident. The Red Shirts are planning fresh street protests this month ahead of a court ruling on whether authorities can seize Thaksins 2.2 billion dollar assets, frozen after the coup that deposed him in 2006. They want to put pressure on every party concerned prior to the verdict day, Suthep said.