Russian opposition leader Alexei Navalny died in an Arctic prison last week
Russian opposition leader Alexei Navalny died in an Arctic prison last week AFP

The mother of Alexei Navalny, Russian President Vladimir Putin's main opponent who died in an Arctic prison last week, said Thursday officials are pressuring her into a "secret" burial for her son.

Lyudmila Navalnaya said she had been shown his body in the morgue in Salekhard, the nearest town to the remote prison, after several days of being barred from seeing her son.

"Yesterday evening they secretly took me to the morgue where they showed me Alexei," she said in a video released on social media by Navalny's team.

But she said investigators wanted her son, who was 47, to be buried "secretly, without a chance to say goodbye."

"They are blackmailing me, they put conditions for where, when and how Alexei should be buried. This is illegal," she said.

Navalny galvanised mass protests against Putin, winning popularity with a series of investigations into state corruption.

He was poisoned with a Soviet-era nerve agent in 2020 and was then jailed in 2021 after returning to Russia following a period of treatment in Germany.

He was sentenced to 19 years in prison on extremism charges and sent to IK-3, a harsh penal colony beyond the Arctic Circle known as "Polar Wolf".

Western governments and Russian opposition figures have accused the Kremlin of being responsible for Navalny's death on February 16.

Hundreds of people have been detained in Russia in recent days at events to pay tribute to Navalny and his widow Yulia Navalnaya has vowed to continue his work.

Lyudmila Navalnaya travelled to Russia's Far North the morning after Navalny's death was announced, hoping to be able to see and retrieve her son's body.

"They want to take me to the edge of a cemetery to a fresh grave and say: Here is where your son lies. I am against that.

"I want that for those of you for whom Alexei is dear, for everyone for whom his death became a personal tragedy, to have the possibility to say goodbye to him."

She said she recorded the video because investigators were "threatening" her.

"Looking me in the eye, they said that if I do not agree to a secret funeral they'll do something with my son's body... I ask for my son's body to be given to me immediately," she said.

The mother also said that investigators had told her they knew the cause of death but did not say what it was.

The Kremlin has refused to say when the body will be handed over and has branded Western accusations as "hysterical".

Putin has so far remained silent on the death of his main political opponent.

Navalny's spokesman Kira Yarmysh said that a medical report on the death shown to Lyudmila Navalnaya "stated that the cause of death was natural".