Ousted former Prime Minister Yingluck Shinawatra greets in a traditional way as she arrives at Parliament before the National Legislative Assembly meeting in Bangkok January 22, 2015. [Photo/Agencies]

"Farmers are the backbone of the country. We must not let that backbone broken,'' said Yingluck during her unfruitful plea to the legislators on Thursday.

Meanwhile, the Office of Attorney General resolved on Friday to lodge a criminal lawsuit against the former premier in court on duty-negligence and law-breaking charges involving the rice program.

The case is expected to be submitted to the Supreme Court by Attorney General Trakul Vinitnaipak in one-month time from now.

If convicted guilty as charged, Yingluck might possibly be sentenced to a maximum of 10 years in jail.

Yingluck's brother, former Thai leader Thaksin Shinawatra who has remained in self-exile overseas following the 2006 coup, alongside 200-plus politicians had been banned from politics for a five-year time several years ago.

Thaksin had been sentenced in absentia by Supreme Court judges in charge of lawsuits against politicians to a two-years jail for power-abusing charges involving a Bangkok land grab scandal during his time as premier.

Security at the Government House and parliament was stepped up with police squads and army troops amid fears that Red Shirt activists, known to have been loyal to the Shinawatra family, might possibly gather en masse in protest of Friday's impeachment.

Former Red Shirt leader and former deputy minister Nattavut Saikua earlier suggested that the pro-Yingluck and pro-Thaksin demonstrators stay calm and not take to the streets for the time being, given current martial rule enforced since last May's coup staged by the then-army chief Gen Prayut himself.