Amnesty International says that a 10-year prison sentence handed to 22-year-old activist detained after spraying graffiti on a statue of the nation's ex-president is a "shocking assault on freedom of expression."

Denis Krivosheev, the group's deputy director for Europe and Central Asia, said in Wednesday's statement that the verdict handed to Giyas Ibrahimov is "an absolute travesty of justice."

A court in Baku sentenced Ibrahimov on Tuesday after finding him guilty of drug offences.

Amnesty said that Ibrahimov, a member of a pro-democracy youth movement, was arrested simply for painting a slogan on a statue, and later tortured into "confessing" to drug crimes. The group called for his immediate release.

International rights groups have repeatedly criticized the ex-Soviet Caspian Sea nation for cracking down on independent media and opposition activists.