Court martial proceedings have begun in the Sri Lankan capital against the former army chief who challenged the incumbent president in this year's election.

Former army chief Sarath Fonseka faced a court martial panel of three generals in a case that could send the opposition figure to prison for years.

The top military spokesman, Army Major General Prasad Samarasinghe, tells VOA News the closed hearing initiated the court proceedings, following Fonseka's arrest two weeks after his defeat in the presidential election.

"One court martial commenced today for alleged involvement in political work while in active service. The second court martial will be tomorrow. That is for the contravention of procedures of military procurement while he was in service," said Samarasinghe.

The proceedings for the first set of charges have been recessed until April 6.

His lawyers say Fonseka is contesting the validity of the court to hear the cases, because the defendant was retired from the army and a civilian when he was arrested.

Fonseka had been hailed as a war hero for his role in defeating the Tamil Tiger rebels, last year.  But after the end of the military campaign, he had a falling out with President Mahinda Rajapaksa, who had previously referred to Fonseka as the world's best army commander.

The top general was promoted and sidelined, subsequently quitting his post as chief of defense staff to eventually become the presidential candidate of a hastily-formed opposition coalition.

Fonseka's supporters call the sedition and corruption charges, which could send him to prison for years, politically motivated.

General Samarasinghe says Fonseka could face additional criminal charges in civil court, as well.

"There are separate inquiries going on by the criminal investigation department about the other alleged offenses he has committed.  After the inquiries, the civil police will file charges at the civil courts," he said.

The opposition says several demonstrations in support of the former general were held while Fonseka's court martial began. They say some protesters were arrested, while others were beaten or dispersed by security forces firing tear gas.

After the election, the government accused Fonseka of planning a coup and conspiring to assassinate the president. He, in turn, accuses the president of rigging the counting of votes from the January 26th election, which showed Mr. Rajapaksa scoring a solid victory.