Russian opposition leader Alexei Navalny's funeral service will be held at a church in southern Moscow on Friday, allies of the politician said.

Authorities finally handed Navalny's body to his mother on Saturday, more than a week after he died in an Arctic prison, in what his allies said was an attempt to stall a public burial.

"Alexei's funeral will be held at the 'Mother of God Quench My Sorrows' church in Maryino on 1 March at 14:00 (1100 GMT). Come in advance," they said in a social media post on Wednesday.

His burial will take place at the nearby Borisov cemetery, they said.

His team said it was difficult to find a church willing to host the service.

"We started to look for a church and a hall for the 1st of March. Everywhere they refused to give us anything. In some places we were told it was forbidden," said exiled ally Ivan Zhdanov.

"We don't care about the message. Alexei needs to be buried ... To have a chance to say goodbye, it is better to come in advance," he added.

Navalny, President Vladimir Putin's most vocal critic, died on February 16 in one of Russia's toughest prisons in northern Siberia, where he was serving a 19-year sentence on charges widely seen as political retribution for his opposition.