The widow of Alexei Navalny has accused Vladimir Putin of mocking Christianity by trying to force the Russian opposition leader’s mother to agree to a secret funeral after his death in a penal colony.

Yulia Navalnaya said in a video released on Saturday that Mr Navalny’s mother, who wants her son’s body returned to her, is being “literally tortured” by authorities who had threatened to bury him in the Arctic prison.

They suggested to his mother that she does not have much time to make a decision because the body is decomposing, Ms Navalnaya said.

“Give us the body of my husband,” she said. “You tortured him alive, and now you keep torturing him dead. You mock the remains of the dead.”

Mr Navalny, 47, Russia’s most well-known opposition politician, died on February 16 in the penal colony, prompting hundreds of Russians across the country to stream to impromptu memorials with flowers and candles.

Authorities have detained scores of people as they seek to suppress any major outpouring of sympathy for Mr Putin’s fiercest opponent before a presidential election he is almost certain to win.

Russians on social media said officials do not want to return Mr Navalny’s body to his family because they fear a public show of support for him.

Ms Navalnaya accused the Russian president, an Orthodox Christian, of killing Mr Navalny.

“No true Christian could ever do what Putin is now doing with the body of Alexei,” she said, asking: “What will you do with his corpse? How low will you sink to mock the man you murdered?”

Saturday marked nine days since the opposition leader’s death, a day when Orthodox Christians hold a memorial service.

Residents of several Russian cities came out to mark the occasion and honour Mr Navalny’s memory by leaving flowers at public monuments or holding one-person protests. At least 27 had been detained in nine Russian cities by 12.45pm on Saturday, according to the OVD-Info rights group.

They included Sergei Karabatov, 64, who laid flowers at a Moscow monument to victims of political repression, along with a handwritten note saying “Don’t think this is the end”.

Also arrested was Aida Nuriyeva, from the city of Ufa near the Ural Mountains, who stood in a street with a sign saying “Putin is Navalny’s murderer! I demand that the body be returned!”

Mr Putin is often pictured at church, dunking himself in ice water to celebrate the Epiphany and visiting holy sites in Russia. He has promoted what he has called “traditional values” without which, he once said, “society degrades”.

Kremlin spokesman Dmitry Peskov rejected allegations that Mr Putin was involved in Mr Navalny’s death, calling them “absolutely unfounded, insolent accusations about the head of the Russian state”.

Musician Nadya Tolokonnikova, who became widely known after spending nearly two years in prison for taking part in a 2012 protest with her band Pussy Riot inside Moscow’s Christ the Saviour Cathedral, released a video in which she accused Mr Putin of hypocrisy.

“We were imprisoned for allegedly trampling on traditional values. But no one tramples on traditional Russian values more than you, Putin, your officials and your priests who pray for all the murder that you do, year after year, day after day,” said Ms Tolokonnikova, who lives abroad.

“Putin, have a conscience, give his mother the body of her son.”

Ms Tolokonnikova is one of several cultural figures who have released videos calling on Russian authorities to return Mr Navalny’s body to his family so they can give him a funeral. His mother and lawyers have been trying to retrieve his body since late last week.

Lyudmila Navalnaya said on Thursday that investigators had allowed her to see her son’s body in the morgue in the Arctic city of Salekhard. She has filed a lawsuit at a court in Salekhard contesting officials’ refusal to release the body, and a closed-door hearing has been scheduled for March 4.

Mr Navalny’s spokesman, Kira Yarmysh, said Lyudmila Navalnaya was shown a medical certificate saying her son died of natural causes.