Alexei Navalny died on February 16 in a Russian prison inside the Arctic Circle
The body of a leading Russian opposition figure Alexei Navalny His spokesman says he was returned to his mother.
In a post on X, Kira Yarmish thanked everyone who requested authorities hand over her remains.
“The funeral has not yet taken place,” he wrote.
Navalny's mother Lyudmila was reportedly asked to agree to a “secret” burial. If she refuses, he will bury his dead in the prison colony.
He has spent the past week in the city near the prison where he died, first trying to confirm the whereabouts of his body and then demanding its return to him.
After signing a death certificate saying he died of natural causes, she was given three hours to agree to her son's “secret” funeral.
Ms. Yarmish said she told her mother that if she did not agree, she would be buried on the grounds of the prison where she died.
However, Lyudmila refused to negotiate with the authorities.
Funeral plans are still unclear, Ms Yarmish said.
“We don't know if the authorities will intervene to make sure this is handled the way the family wants and the way Alexei deserves,” he said.
Earlier on Saturday, Navalny's widow, Yulia Navalnaya, accused Vladimir Putin of holding her late husband's body “hostage” and demanded his unconditional release.
“Give us my husband's body,” she demanded in a video address.
“You tortured him alive, and now you continue to torture him. You mock the remains of the dead.”
Mrs Navalnaya again accused the Russian president of being behind her husband's death.
The Kremlin has denied the allegations, saying Western reaction to the death was “hysterical”.
Navalny died on February 16 in a Russian prison inside the Arctic Circle.
Little is known about what happened to him. His group has offered security officials a €20,000 ($22,000; £17,000) reward and help to leave Russia in exchange for information about his death in prison.
For years, he was the Russian leader's most vocal critic.
In August 2020, Navalny was poisoned with a Novichok nerve agent by a team of assassins from the Russian secret services.
Airlifted to Germany, he recuperated there before returning to Russia in January 2021, where he remains in prison.
Attempts to commemorate his death have been met with a harsh response from Russian authorities, with makeshift memorials removed and hundreds arrested.
“Friend of animals everywhere. Devoted analyst. Total alcohol scholar. Infuriatingly humble food trailblazer.”