
People's Alliance for Democracy leaders lead some 1,500 protesters from the Government House to besiege the Parliament at about 8pm on Monday.
First batch of anti-government protesters arrived at the Parliament at about 8.15pm after marching from the Government House where they have occupied since August.
The demonstrators manged to fully block the Parliament at about 10pm.
Before they marched to the Parliament, PAD's leaders announced on stage in the Government House that Somchai Wongsawat Government has lost legitimacy to govern the country.
Some protesters used barriers to block all roads leading to the Parliament.
Dozens of police were seen setting up barriers inside the Parliament, chaining all entrances and guarding to prevent protesters from entering the compound.
Leaders of People's Alliance for Democracy who led the protests told the protesters not to try to invade into the Parliament compound.
PAD leaders said earlier that they and the protesters will stay overnight in front of the Parliament where Members of Parliament are scheduled to attend budget debates on Tuesday.
They will block the Somchai government's three-day policy address, starting Tuesday as they said Somchai and his cabinet have lost legitimacy to administer the country.
Not all protesters moved to the Parliament, some were staying there to prevent police from raiding the compound.