The group had revoked the label from Navalny in February over past comments he had made. The activist has been criticized in some corners for past statements against illegal immigration, and for attending a nationalist march years ago.

After a review of the process, Amnesty said that while "some of Navalny's previous statements are reprehensible and we do not condone them in the slightest," the group also recognized "that an individual's opinions and behaviour may evolve over time."

"Our approach has been refined to not exclude a person from designation as a Prisoner of Conscience solely based on their conduct in the past," they said. "It is part of Amnesty's mission to encourage people to positively embrace a human rights vision and to not suggest that they are forever trapped by their past conduct."

Amnesty also criticized "the Russian government and its supporters" for using the initial revocation "to further violate Navalny's rights."

"Amnesty International made a wrong decision, which called our intentions and motives into question at a critical time, and apologises for the negative impacts this has had on Alexei Navalny personally, and the activists in Russia and around the world who tirelessly campaign for his freedom," they said.

The imprisonment of the 44-year-old Russian opposition leader has prompted large protests in many parts of the country, and security forces have rounded up thousands of people at recent rallies.

He was arrested in January when he returned to Moscow from Germany, where he had been recovering from being poisoned, and sent to prison in February after a Moscow court on replaced a suspended sentence with jail time due to violations of his probation while out of the country.

On April 23 he said he was ending a weekslong hunger strike, following a warning from doctors close to him that he was close to death.