Human Rights activist Sen was sentenced to life time incarceration by a trial court in Raipur on Dec 24, 2010, on sedition charges over his connections with Maoist ideologue Narayan Sanyal.
A group of 40 Nobel laureates from 12 different countries have written a letter to the Prime Minister and pressed for Sen's immediate release on bail. They said that they hoped Sen's appeal would be immediately heard without delay under the highest standards of Indian law.
The Nobel laureates have described Sen as an "exceptional, courageous and selfless colleague, dedicated to helping those in India who are least able to help themselves."
Dr Venkatraman Ramakrishnan, who got a Nobel in 2009 and 91-year-old French scientist Francois Jacob, who got a Nobel Prize in 1965 are among the 40 laureates.