BANGKOK

Thai authorities have dealt a double blow to ousted Prime Minister Yingluck Shinawatra and her powerful family, banning her from politics for five years and proceeding with criminal charges for negligence that could put her in jail.

The moves could stoke tension in the politically divided country still living under martial law after the military seized power in May, toppling the remnants of Ms Yingluck's government to end months of street protests.

The ban and the legal case are the latest twist in 10 years of turbulent politics that have pitted Ms Yingluck and her brother Thaksin, himself a former prime minister, against the royalist-military establishment which sees the Shinawatras as a threat and reviles their populist policies.

Yingluck will face criminal charges in the Supreme Court and if found guilty faces up to 10 years in jail, the Attorney General's Office said on Friday.

The charges against the country's first female premier, who was removed from office for abuse of power in May days before the coup, concern her role in a scheme that paid farmers above market prices for rice and cost Thailand billions of dollars.

Ms Yingluck has vowed to fight the charges.

"Thai democracy has died along with the rule of law," she said in a statement posted on her Facebook page.

"I will fight until the end to prove my innocence, no matter what the outcome will be. And most importantly, I want to stand alongside the Thai people. Together we must bring Thailand prosperity, bring back democracy and truly build justice in Thai society."

There was no sign of protests on the capital's busy streets as residents adhered to the junta's ban on public gatherings.

Security was tightened around the parliament building where the military-stacked legislature voted Ms Yingluck guilty in a separate impeachment case for failing to exercise sufficient oversight of the rice subsidy scheme.

The retroactive impeachment at the National Legislative Assembly (NLA) carries with it a five-year ban from politics.

A vote to impeach required a three-fifths majority among NLA members, who were hand-picked by the junta of coup leader and Prime Minister Prayuth Chan-ocha. Around 100 of the 220 members are former or serving military officers.