Yingluck Shinawatra was sentenced for mishandling a failed rice scheme, in a verdict read in absentia after she fled Thailand last month.
Thailand's top court sentenced ousted premier Yingluck Shinawatra to five years in prison for mismanaging a rice subsidy scheme, a verdict read in absentia ruled on Wednesday.
Yingluck fled the kingdom last month, after her administration was toppled in a 2014 coup. She was later put on trial for negligence over the scheme, which is said to have cost billions of dollars.
She maintained her innocence and accused the ruling junta of a political witch-hunt.
But the Supreme Court in Bangkok then deemed her guilty, arguing that she failed to stop corruption and losses in the rice programme.
"The court found that the defendant is guilty as charged ... the court has sentenced her to five years in prison and the court also unanimously agreed that the sentence will not be suspended," a judge said.
What happens next?
The verdict makes Yingluck's return to the kingdom increasingly unlikely. It ruled that the leader "should have designated reasonable and effective regulations that could concretely prevent loss from the beginning of the programme."
"The defendant did not take such precaution therefore contributing to huge losses to farmers, state budget, Ministry of Finance, the country and the people," it continued.
After attending dozens of hearings in a trial that lasted more than one year, Yingluck failed to turn up for a ruling originally scheduled for August 25 – a day of high drama that left the kingdom dumbfounded.
Scheme costs $10 billion
The 50 year old has not made any public appearances or comments since pulling the vanishing act.
But there are widespread reports she joined her billionaire brother Thaksin, a former prime minister ousted in a 2006 coup, in Dubai.
Thaksin has kept a home in the city since he fled Thailand in 2008 to avoid jail for a corruption conviction.
The two siblings lie at the heart of a political battle that has gnawed at Thailand for more than a decade.
Emerging on the scene in 2001, they won the loyalty of the rural and urban poor with groundbreaking welfare schemes in a sharply unequal country.
But their rise angered Bangkok's army-allied elite, which repeatedly assailed their elected governments with coups or court rulings.
Yingluck's downfall revolved around a scheme that saw her government purchase rice from farmers at nearly twice the market price.
It was wildly popular in the rural heartlands but slammed by critics as a costly and graft-riddled handout.
"There was corruption in every step of the rice pledging programme," the court verdict said, adding that it cost the country nearly $10 billion.
Nine judges voted unanimously to find Yingluck guilty in a verdict reading that took four hours, and a warrant was issued for her arrest.
Norrawit Larlaeng, a lawyer for Yingluck, told reporters outside the court that an appeal was being discussed.
A former commerce minister in her government was jailed for 42 years last month for falsifying government-to-government rice deals in connection with the subsidy scheme.