BANGKOK (REUTERS) - Thailand's former prime minister Thaksin Shinawatra on Wednesday (Aug 30) made his first public comment since his sister Yingluck fled the country last week, breaking a long silence with a Twitter post that appeared to denounce the Thai justice system as tyrannical.

Yingluck, 50, whose government was ousted by the military in 2014, disappeared from Thailand last week, shortly before a Supreme Court verdict in a negligence case against her. She had faced up to 10 years in prison if found guilty.

In his comment on Twitter, Thaksin quoted the 18th century French philosopher Charles de Montesquieu.

"Montesquieu once said 'There is no crueler tyranny than that which is perpetuated under the shield of law and in the name of justice'," Thaksin wrote on his official Twitter page.

The post, which appeared in both English and Thai, was his first on that page since 2015. The message was retweeted more than 1,000 times within 40 minutes.

A former telecommunications tycoon, Thaksin was ousted in a 2006 coup and lives in self-exile to avoid a 2008 graft conviction he says was politically motivated.

Yingluck disappeared ahead of the court verdict last Friday in her trial for negligence over a costly rice subsidy scheme that helped to bring her to power in a 2011 general election.

She was forced to step down days before a May 2014 coup against her government, after a court found her guilty of abuse of power in connection with a civil service posting.

Supporters of Yingluck and Thaksin have accused the courts of bias in frequent ruling against the Shinawatras and their allies.

Last week, junta chief Prayuth Chan-ocha said the government had no influence over the courts.

'PERSECUTION'

Thaksin re-shaped Thai politics after a building business empire, winning staunch support with populist policies that raised living standards, especially among the rural poor, and propelled him or his loyalists to victory in every election since 2001.

But Thaksin also posed a challenge to the royalist-military establishment, which denounced him as corrupt, setting up a struggle that has defined Thai politics for most of the past 15 years.

His seemingly defiant post on Twitter will be viewed with interest on both sides of the divide.

Winthai Suvaree, a spokesman for the junta, declined to comment on Thaksin's post.

In March, Thaksin accused the ruling junta in a Facebook post of bullying him over a US$500 million (S$677 million) tax bill and said he could be ruled out of any reconciliation efforts.

Yingluck has accused the military government of political persecution. She pleaded innocent to the negligence charge against her.

Aides say Yingluck left Thailand after getting information that she would be given a heavy sentence. They and sources at her Puea Thai Party said she is now in Dubai with Thaksin, who has a home there.

In a statement on Tuesday, the Puea Thai Party did not refer explicitly to Yingluck's departure but said it would overcome the obstacles it faced and was committed to democracy.

The military government has promised to hold an election next year. The support the Shinawatras command will be closely watched.