Rights activist Binayak Sen has challenged in Chhattisgarh High Court the life sentence given to him by a local court after being convicted for sedition and links with Maoists, saying his involvement in the alleged crime was not proved beyond reasonable doubt.

58-yer-old Sen's counsel Mahendra Dubey filed an appeal against his conviction yesterday, contending that after a thorough examination of the lower court's judgement it has become clear his involvement in the alleged crime was not proved beyond reasonable doubt.

"Circumstantial evidence, which form the basis of the judgement, lack cohesion and arguments of the defence were ignored," Dubey said in the petition challenging the December 24 order of Additional District and Sessions Judge B P Verma.

Dubey further said, "The lower court neither properly followed the procedure laid down for trial of criminal offences nor explained the evidence adduced in accordance with law."

The conviction has triggered angry reactions from fellow activists within and outside the country.

Sen, Vice-President of People's Union of Civil Liberties, was convicted for sedition and sentenced to life in prison along with Naxal ideologue Narayan Sanyal and Kolkata businessman Piyush Guha for colluding with Maoists to establish a network to fight the state.

Additional District and Sessions Judge B P Verma held the trio guilty under provisions of section 124A (sedition)and 120 B (conspiracy) of IPC and Chhattisgarh Special Public Security Act.

Sen, a paediatrician by training, had been accused by the prosecution of acting as courier for Sanyal, who was in jail, by carrying his messages and letters to the underground Maoists.

Sen was arrested on May 14, 2007 from Bilaspur and was in jail for two years before being granted bail by the Supreme Court in May last year.