Jailed Kremlin critic Alexei Navalny has tested negative for the coronavirus, his lawyer Olga Mikhailova said on Wednesday, adding that he has taken a second test.

Navalny, 44, an opponent of President Vladimir Putin, announced that he going on a hunger strike last week in protest at what he said was the refusal of prison authorities to treat him properly for acute back and leg pain.

Human rights group Amnesty International earlier on Wednesday said Navalny had been incarcerated in conditions that amount to torture and may slowly be killing him.