Hundreds of anti-government protesters besieged the Parliament House for hours Wednesday and stormed into the compound before they withdrew and dispersed upon their leader's request.

Prime Minister Abhisit Vejjajiva has announced later Wednesday to cancel his trip to the U.S. on April 10 for the World Nuclear Conference after the chaos at Parliament House.

The then-ongoing cabinet meeting was forced to suspend proceedings and the scheduled House meeting had to be canceled as the red-shirted protesters from their main rally site Phan Fah Bridge arrived at the parliament by 11:30 a.m., their latest move in a prolonged rally to pressure Abhisit to dissolve the House of Representatives and hold a general new election.

The protesters surrounded the compound and stopped anybody from getting out and once broke into the yard at about 12:20 a.m., but retreated soon to stay outside after the "red-shirts" co-leader Jatuporn Promphan asked them to keep a peaceful demonstration.

Earlier one leader gave an ultimatum at about 11:55 a.m., demanding the security forces to "open the gate in 19 minutes", or else they would break into the compound.

Prime Minister Abhisit left the Parliament House before the " red-shirts" arrival while the Deputy Prime Minister in charge of security affairs Suthep Thuagsuban and many MPs were still inside.

Some MPs had to climb over the wall to get out though Suthep, PM's Office Minister Satit Wongnongtaey, and acting government spokesman Panitan Wattanayagorn were later picked up by a helicopter to the Peace-keeping Operation Command (PKC) at the 11th Infantry Regiment in Bangkok.

The situation once turned highly intense when some "red-shirts" snatched two loaded guns from the police outside the Parliament House compound.

Also, "red-shirts" co-leader Arisman Pongruangrong claimed two tear gas grenades were found at the parliament compound and claimed that's the reason they broke into the compound.

Responding to him, Metropolitan Police Division 1 Commander Police Major General Wichai Sangprapai said the police is conducting investigation and promised to explain in half an hour.

Over 1,000 thousand security men were deployed around to maintain law and order and dozens of police vehicles arrived at the scene to strengthen the security there.

Before Chai Chidchob, Speaker of the House of Representatives, announced to cancel the scheduled House meeting at about 11:20 a.m. , the cabinet meeting, held in the Parliament House, was also abruptly stopped.

However, prior to the "red-shirts" arrival, the cabinet resolved to extend the Internal Security Act's (ISA) enforcement to April 20 in Bangkok and nearby areas to ensure security.

The ISA imposition has been imposed for the whole area of capital Bangkok, while only two districts of Nonthaburi and five other districts of Samut Prakan will be under its enforcement.

At about 13:45 p.m. the "red-shirts" started dispersing from the parliament compound after Deputy Premier Step and the MPs left the parliament.

Meanwhile, during the protest at the parliament, another "red- shirts" core leader Nattawut Saikua told some protesters to move to stage a rally at Thaicom satellite firm in Nonthaburi province, where their DStation television is transmitted.

The rally at Thaicom satellite firm in Nonthaburi province has occurred after the "red-shirts" have learnt the government has sought blocking of the transmission of the broadcast of their television.

Nattawut told the "red-shirts" to remain at Thaicom satellite firm in Nonthaburi, which is next to Bangkok, in order to monitor the situation.