Thai police are trying to keep anti-government protesters from entering the grounds of the prime minister's office building. As Ron Corben reports from the Thai capital, anti-government groups are escalating their efforts to push Prime Minister Samak Sundaravej out of power.

More than 8,000 police are keeping a close watch on thousands of protesters who gathered around the main government building in Bangkok on Friday.

March organizers have vowed lay siege to the offices of Prime Minister Samak Sundaravej until he resigns. The police have warned the protesters they will not be allowed to enter the compound.

Mr. Samak heads a coalition government led by the People's Power Party, which is closely linked to former Prime Minister Thaksin Shinawatra. Mr. Shinawatra was ousted in a military coup in 2006, but remains a deeply divisive figure in Thailand.

In May, the People's Alliance for Democracy began a series of protests prompted by the government's plans to amend the constitution. The amendments could have halted corruption investigations of Mr. Thaksin.

The People's Alliance for Democracy also led massive demonstrations against the Thaksin government before the coup in 2006, accusing the former leader of abuse of power and corruption.

Thepchai Yong, managing director of the Thai Public Broadcasting Service, says the country is deeply divided between those who support Mr. Thaksin and those who oppose him.

"In the past we had some figures - some respectable figures - who can intervene. But now it seems that there are two opposing forces going at each other's throat and we don't see anybody that can come between and make peace between these two forces," said Thepchai.  "It's a very dangerous time, very, very dangerous."

Many political analysts here say it is unlikely there will be a repeat of the 2006 military coup.

"The military will try to be neutral towards this kind of increasing conflict," said Sompob Manaragnsan, a director of the Institute of Asian Studies at Chulalongkorn University.  "I don't think that they are going to intervene, if they are not going to have a serious confrontation or uncontrollable violence."

However, military commanders say the army is ready to take action if the demonstrations turn violent.

Fears of a violent confrontation have led to billions of baht being wiped off the stock exchange of Thailand in the past month. The SET index has lost more than 13 percent.