Dmitry Vorobyovsky, a prominent anti-Kremlin protester in the southwestern city of Voronezh, was forcibly detained by paramedics last Friday, according to Amnesty International.

“The court refused to accept the demands of the psychiatric hospital staff” who were seeking to intern the activist, his lawyer Sergei Lotkiev told RIA Novosti news agency.

“Vorobyovsky was released (and he returned) home” after a three-hour court hearing, he added.

Amnesty International earlier this week denounced the activist’s detention.

“At the hospital he was tied to a bed for three hours during which he was injected with an unknown substance and given pills against his will,” Amnesty said in a statement Monday.

The rights group said the alleged medical grounds for the 52-year-old’s “detention and forcible treatment” remain unclear and that he “may have been detained because of his outspoken criticism of government policy”.

Psychiatric treatment was widely used during the Soviet period to try to crush dissidents who criticised the system.

Russian authorities have passed a raft of legislation in recent years to make it increasingly difficult to protest against the rule of strongman leader Vladimir Putin.