Thaksin was toppled from power by a 2006 military coup after being accused of abuse of power, corruption and disrespect for the monarchy. He is living in self-imposed exile to avoid serving a prison term from a 2008 conviction on a conflict of interest charge.

Yingluck, who inherited the leadership of Thaksin's political machine and was elected prime minister in 2011, became a proxy target for his enemies as well.

Despite her absence Wednesday, scores of supporters turned up at court but were outnumbered by police.

"We can only accept the court's decision," said Pattana Meethai, 63, one of the supporters. "I'm not surprised. I'm quite used to the courts ruling in this fashion."

The rice subsidy scheme was a flagship policy that helped Yingluck's Pheu Thai Party win the 2011 general election. The government paid farmers about 50 percent above what they would have received on the world market, with the intention of driving up prices by warehousing the grain.

Instead, other rice-producing countries captured the market by selling at competitive prices. Vietnam as a result replaced Thailand as the world's leading rice exporter.

Prosecutors argued that Yingluck was guilty of dereliction of duty. Her critics describe the overriding motive of the rice subsidy program as political, an effort to buy the loyalty of rural voters with state funds.

A co-defendant, her commerce minister, received a 42-year prison sentence for concocting a false government-to-government rice sale, which was one of the allegations cited by the court in its verdict against Yingluck.

Up until Aug. 25, Yingluck had vowed to remain in the country and fight any charges against her, which posed a potential threat to the ruling junta.

Acquitting Yingluck risked alienating people who took part in protest movements in late 2013 and early 2014 and seized government buildings and disrupted snap elections, setting the stage for the military coup.

Jailing Yingluck, on the other hand, threatened to turn her into a martyr and pave the way for a new era of upheavals. That led to speculation that the junta may have been aware of Yingluck's intention to flee and allowed it to happen, though the junta has denied it.

Thaksin's mostly rural supporters, who delivered him unprecedented electoral victories, believe his only offense was challenging the power of the country's traditional elite, led by monarchists and the military, and supported by the urban middle class.

They believe his appeal, earned from populist policies benefiting the less well-off rural majority, threatened the traditional ruling class' privilege. 

The junta that took power in 2014 has pushed through reforms ostensibly to curb corruption and money politics by limiting the power of elected politicians, but are clearly aimed at keeping Thaksin from power. It has delayed holding new elections as long as the possibility exists that Thaksin's political machine could stage a comeback. (AP)