The seven-hour verdict that cost Thaksin $1.4bn

Former prime minister convicted of abusing power in office claims court's ruling was rigged, raising fears of more unrest

The Thai authorities were last night braced for demonstrations after the country's highest court seized $1.4bn of former prime minister Thaksin Shinawatra's assets and ruled that the exiled tycoon had abused his power in office.

In a marathon verdict that took seven hours to deliver, the Supreme Court said the one-time owner of Manchester City Football Club had concealed his ownership of shares in a family business during his five years he held the post. During that time, the court said, he had engineered government policy to benefit the conglomerate.

Last night, in a message delivered by video link to around 800 of his supporters, the telecommunications magnate said he had not been surprised by the verdict. "The Thai law is like an assumption. It severely fails to meet international standards," he said, as some of his supporters cried and other shouted in frustration.

In advance of "Judgment Day" the authorities had deployed thousands of additional police and security guards in anticipation of protests by Mr Thaksin's "red shirts" supporters. The court's nine judges were assigned body-guards and bullet-proof vehicles. Mobile phone signals were jammed to prevent the remote detonation of explosives.

Thailand has been racked by political turmoil ever since Mr Thaksin was ousted in a military coup in 2006. After a period of military rule, subsequent elections saw allies of the tycoon assume the premiership but his opponents never ceased their efforts to undermine his supporters and two prime ministers close to Thaksin were forced from office. Previous demonstrations brought Bangkok to a standstill and forced the closure of international airports, costing Thailand millions of dollars in tourist earnings. In December 2008, the Eton-educated Abhisit Vejjajiva, leader of the opposition Democrat Party, took charge with a slim majority. While his emergence brought some stability, the government has not addressed key issues.

The verdict against Mr Thaksin, who still retains huge support among Thailand's rural poor, was unanimous. The court found him guilty on all five charges, which included fixing government policy to benefit his family company, Shin Corp. One of the most prominent cases involved a $127m low-interest loan to Burma in 2004, which the court ruled the then prime minister had endorsed to secure its purchase of satellite services from Shin Satellite, then controlled by members of his family.

Mr Thaksin, previously convicted in absentia of corruption and sentenced to two years in jail, had denied all the charges. "This is total political involvement. The government knew the result in advance," he told his supporters from Dubai. "I've been prepared for the result since yesterday. I knew that I would get hit, but they are kind enough to give me back 30 billion [baht]."

Things could have been worse for the 60-year-old tycoon. In the aftermath of the 2006 coup, the courts froze $2.3bn of his assets. this time, the court decided not to seize the money he had amassed before becoming prime minister, saying it "would be unfair". The government hopes that yesterday's ruling will lead to a return of stability. At the same time, it has increased security amid fears that members of the United Front for Democracy Against Dictatorship, also known as the "red shirts", could launch fresh protests. "We hope for the best," said Panitan Wattanayagorn, a government spokesman. "Of course many people fear for the worst but we are ready to manage whatever comes."

Mr Thaksin's supporters will see yesterday's ruling as the latest in a series of establishment blows against the populist who won two sweeping electoral victories before being swept from power by a conservative coalition that inaccurately called itself a pro-democracy movement. Many believe he has been hounded because Thailand's urban ruling class felt threatened when he empowered the country's rural poor with a series of social welfare programmes.

Thitinan Pongsudhirak, a political scientist from Bangkok's Chulalongkorn University, told the Associated Press: "[This will] not put an end to Thailand's crisis because now Thaksin's supporters, the Red Shirts, have evolved into their own force to be reckoned with."