New Delhi  - Twenty-two Nobel laureates have appealed to the Indian government to release human rights activist Binayak Sen, jailed for a year in the central state of Chhattisgarh, news reports said Monday.

The appeal, made in a letter to Prime Minister Manmohan Singh and President Pratibha Patil, said Sen should be allowed to travel to Washington to receive the Jonathan Mann Award for Global Health and Human Rights on May 29, the Times of India reported.

Sen, 58, has been in jail since May 14 after he was charged by the Chhatisgarh government for having links with Maoist rebels in the state. He has denied the charge.

"We wish to express grave concern that Dr Sen appears to be incarcerated solely for peacefully exercising his fundamental human rights," the letter signed by Nobel Prize-winning economists and scientists said.

The laureates also charged that the two internal security laws under which Sen had been charged, an unlawful activities act and a state public security act do not adhere to international human rights standards.

The signatories included economists Kenneth Arrow and Finn Kydland, scientists Claude Cohen-Tannoudji, Charles Townes, Yuan Lee and John Walker.

The Global Health Council, an alliance of medical organizations and professionals, chose Sen, trained as a pediatrician, for the award last month.

According to the award citation, Sen focused his life's work on improving the health care and living conditions of the poor in the tribal regions of central India.

He was also chosen for his unwavering commitment to civil liberties and human rights. Sen is the vice president of the Indian human rights group People's Union for Civil Liberties.

Local media reported that Sen was charged with being a member of a terrorist organization after Sen criticized the manner in which the Chhattisgarh government was dealing with the Maoist insurgency.

The reports said that the charges on Sen were serious enough for him to be punished with a life sentence or the death penalty. (dpa)