BANGKOK, Jan. 13 -- Tens of thousands of anti- government demonstrators took to the streets on Monday, paralyzing traffic in the inner part of the capital city in a prolonged political protest known as "Bangkok shutdown" .

The anti-government protesters, calling themselves People's Democratic Reform Committee and led by former deputy premier Suthep Thaugsuban, gathered on several major streets in the heart of the city, keeping motorists out of the way. Sandbags and tires were stacked up and heavy-duty trucks parked at Chaeng Wattana and Lad Prao intersections to block the traffic headed for the inner part of the city.

Makeshift platforms were set up at several intersections circled by protesters, many of whom have come from the provinces. The spots currently swarmed by the protesters are those in Pathumwan, Saladaeng, Lad Prao, Victory Monument, Lumpini, Rajprasong and Asoak areas.

Suthep, who organized the mass protests since the last few months, said the "Bangkok shutdown" could possibly be going on indefinitely to mount pressure upon the caretaker government headed acting premier Yingluck Shinawatra to step down.

Yingluck held a meeting with high-level government officials in charge of security affairs at the headquarters of the Office of Defense Undersecretary in Muang Thong Thani area, several kilometers from the protester-occupied Chaeng Wattana intersection.

Acting Transport Minister Chatchart Sithipun said the traffic in the capital would not be very critical on Monday because many people have chosen to avoid the protester-occupied streets or taken leave from work but it might get far worse when they return to work on Tuesday or later in the week.

Many Bangkok schools have closed, keeping the children at home until Tuesday or Wednesday.

Unarmed police and soldiers were deployed in the compounds of varied government premises where the protesters might probably invade and occupy as they earlier did to the finance ministry in Samsen area and a government complex in Chaeng Wattana area.

Stand-offs and clashes between anti-government protesters and others might possibly occur in Chaeng Wattana, Lad Prao and Victory Monument areas, according to the government-run Center for Administration of Peace and Order.