A Russian court is expected to start hearings on April 15 on imprisoned environmental activist Yevgeny Vitishko's request for early release.
Vitishko, 41, was jailed after raising concern about the environmental impact of the 2014 Winter Olympics in Sochi.
He was handed a three-year suspended sentence in 2012 for spray-painting a fence in a forest near Sochi to protest what he said was illegal construction.
But In December 2013, a local court in southern Russia ruled that he had violated the terms of the sentence and sent him to prison.
A higher court upheld that decision in February 2014.
On April 14, Amnesty International urged Russian authorities to immediately release Vitishko, who started a hunger strike on April 7.
Amnesty has named Vitishko a "prisoner of conscience" and the prominent Moscow-based human rights group Memorial considers him a political prisoner.