Alexei Navalny's mother said that she saw his body, but added that the Russian authorities were pressuring her to allow his burial “in secret.”
In a video address, Lyudmila Navalnaya said she was taken to the morgue on Wednesday evening.
She said she signed the death certificate. Allies of the former opposition leader said they claimed he died of natural causes.
Navalny's widow said he was killed by Russian authorities.
Lyudmila Navalnaya said the law required authorities to hand over her son's body, but said she was being “blackmailed” because they refused to do so. She claimed that the authorities were determining the conditions for her son's burial, including the place, time and manner of his burial.
She said: They want to take me to the edge of the cemetery to a new grave and say: Here lies your son.
Navalnaya, who traveled to the northern Russian town of Salekhard after news of her son's death in a nearby penal colony, said she had been threatened by authorities.
“They look me in the eye, saying that if I don't agree to a secret funeral, they will do something with my son's body.
“Investigator Vorobayev told me frankly: Time is not on your side, the body is decomposing.”
She was speaking in a video clip posted on her late son's YouTube channel, and ended the speech by demanding that his body be returned to her.
There was no immediate response from the Russian authorities.
Navalny died in a prison colony on February 16.
His widow, Yulia Navalnaya, claimed he was killed on the orders of Russian President Vladimir Putin and vowed to continue his struggle.
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