Amnesty on Friday urged Bahrain to immediately release a rights activist jailed for his role in anti-regime protests, warning his life is at risk after a hunger strike of more than seven weeks.
Abdulhadi al-Khawaja had lost 16 kilograms (35 pounds) since beginning a hunger strike 50 days ago, the London-based human rights watchdog said, citing the activist's lawyer.
The 52-year-old was arrested in April last year for leading pro-democracy protests that had been crushed the month before by security forces in the Sunni-ruled Gulf monarchy.
"Bahrain must ensure that Al-Khawaja is released immediately and unconditionally", Philip Luther, Amnesty International's Middle East and North Africa director, said in a statement.
"The Bahraini authorities have made pledges that they would release people who were imprisoned for exercising their right to freedom of expression, but the continued imprisonment of Abdulhadi al-Khawaja demonstrates that they are not serious about fulfilling such promises."
Amnesty said it considered Khawaja, a former member of rights group Frontline, to be a prisoner of conscience.
It alleged he was tortured in custody and sentenced to life in a "grossly unfair trial" last June.
Khawaja began his hunger strike on February 8 in protest at his sentence, and had recently reduced his intake of glucose and minerals.
During his trial, he had told the court he was tortured in prison, and had suffered a cracked jaw and skull, said Amnesty, which added the allegations have yet to be investigated.
A military court sentenced Khawaja to life in prison and the ruling was upheld in September by the National Safety Court of Appeal, another military tribunal.
The Court of Cassation is due to hear another appeal on April 2.