Allies of deceased Russian opposition leader Alexei Navalny say his body has been returned to his mother.

A spokesperson for Navalny's support group posted the news on social media on Saturday. Navalny was reported to have died in an Arctic prison colony in the Yamalo-Nenets autonomous district on February 16.

The spokesperson said they did not know yet whether the family could hold a funeral as they wanted.

Authorities had refused to hand over Navalny's body despite repeated requests from his mother, Lyudmila Navalnaya. The spokesperson said on Friday that Lyudmila received a phone call from authorities and was pressured to agree to burying her son in secret within three hours, or else he would be buried on prison grounds.

Criticism is mounting in the West over speculation that the administration of President Vladimir Putin was responsible for the activist's death. It is unclear whether the family will be able to verify the cause of his death as eight days have passed.

Sources, including a human rights group, say that people across Russia continued to pay tribute to Navalny or to protest the invasion of Ukraine on Saturday. Authorities have reportedly detained more than 30 people.