Anti-government protesters in Thailand vow to step up pressure on the government and the Supreme Court ahead of a crucial ruling involving former Prime Minister Thaksin Shinawatra.

Protesters are expected to gather Friday in Bangkok, in front of Thailand's anti-corruption commission, in the first stage of a campaign against the government.

The main anti-government group, the United Front for Democracy Against Dictatorship, plans a series of protests throughout the country over the next several weeks. They want to oust the government and make it possible for former Prime Minister Thaksin Shinawatra to return to the country.

They also want the Supreme Court to rule in favor of Mr. Thaksin on February 26. The court is expected to say whether the government can seize more than $2 billion from Mr. Thaksin that it says were acquired illegally.

Sompob Manarangsan, an economist at Chulalongkorn University, says Thailand is again entering a difficult political phase as Mr. Thaksin's supporters and his opponents face off.

"It's one of the most critical periods, I think, about the confrontation of the two sides because the problem for the judges to make a decision about Thaksin's assets," he said.

The Thai political landscape has been volatile since Mr. Thaksin, a former telecommunications entrepreneur, came to power nearly a decade ago. His policies won him support among the rural and urban poor and working class.

But the Thai middle class and academics accused him of being corrupt and abusing power. He was ousted in a coup in 2006.

The new government investigated him for corruption and in 2008 Mr. Thaksin fled Thailand to avoid a two-year prison sentence.

The government says it will allow the pro-Thaksin protests but it will use a security law that allows for the military to help police quell demonstrations if things get out of hand.

Spokesman Panitan Wattnayagorn says the government wants to avoid more riots like those seen last year when Mr. Thaksin's supporters, known as red shirts, took to the streets.

"We will do our best and we are certain that once everything is in place and once plans are implemented these preventative measures should be able to control the situation or stabilize the situation and people can demonstrate peacefully," he said.

Kokaew Pikulthong, a spokesman for United Front for Democracy against Dictatorship, says the court verdict will determine the ultimate size of the protests.

"If the case of Khun Thaksin's assets comes out without any reasonable reason or explanation then it will cause the people to think it's unfair - then many people many people may go out more and more when we set up the bigger protest," he said.

The anti-government leaders say they hope to have more than a million people join in their protests in the coming days.