Twenty two Nobel laureates have called for the release of India's best-known "barefoot doctor" from jail, where he has languished for almost a year on terrorism charges. If convicted he faces the death sentence.
Binayak Sen, 58, an award-winning paediatrician who shot to prominence a quarter of a century ago by treating tribal communities for free in the forest region of India's Chhattisgarh state, was arrested last May charged with carrying notes from a member of a Naxalite Maoist rebel movement, who was his patient in prison.
Sen, a human-rights activist who frequently visited jails to treat inmates, protests his innocence. He is now accused of being a member of a terrorist organisation and conspiring to wage war against the government. He has been denied bail and his trial began last month.
Sen is famous for drawing up one of the most successful community-based primary healthcare schemes in India, based on the Mitanin, the local barefoot health worker who gives the rural poor invaluable advice on preventative health.
His incarceration has alarmed many prominent intellectuals but this latest appeal, signed by some of the world's most illustrious names in economics, physics, chemistry and medicine, goes further by questioning the grounds on which he was taken into custody.
The 22 academics called for his release in time to accept an international health and human rights award in Washington this month.
In their letter to India's prime minister, Manmohan Singh, the 22 expressed "grave concern that Dr Sen appears to be incarcerated solely for peacefully exercising his fundamental rights". They also said the two internal security laws under which he had been charged, "do not comport with international human rights standards".
Sen's wife, Ilina, said: "The state has found 85 witnesses. By the end of June we may have heard eight. The trial could last years."
Chhattisgarh is the epicentre of the Naxalite rebel revolt that seeks to overthrow the Indian government. It is an armed movement which has been gaining ground across a swath of the country's mineral-rich forest belt. Governments in states such as Chhattisgarh have launched crackdowns on villages suspected of supporting the Naxalites, using local militias to flush out "leftwing rebels".
The security sweeps have emptied many districts which sit above valuable mining lands, prompting human-rights activists to complain that the displacement of 100,000 villagers in Chhattisgarh has aided the state's drive to exploit its mineral wealth.
Sen was a vocal critic of the state's push for "resource-centred development", which he said trampled on the rights of the poor. The state government defended its decision to arrest him. "We have documentary proof of wrongdoing. We are sure of the case," said Shivraj Singh, Chhattisgarh's top civil servant.
The Nobel laureates who signed the letter include Kenneth Arrow and Finn Kydland (economics); Claude Cohen-Tannoudji and Charles Townes (physics); Peter Agree, Robert Curl, Johann Deisenhofer, Harold Kroto, Yuan Lee, John Polanyi, F Sherwood Rowland, Jens Skou and John Walker (chemistry); Paul Greengard, Roger Guillemin, François Jacob, Eric Kandel, Craig Mello, Richard Roberts, Phillip Sharp, Harold Varmus and Torsten Wiesel (physiology or medicine).