Alexei Navalny's supporters on Saturday claimed Russian authorities of being "killers" who were "covering their tracks" by refusing to hand over his body, as the Kremlin stayed silent despite Western accusations and a flood of tributes to the late opposition leader, reports BSS.

The 47-year-old Kremlin critic died in an Arctic prison on Friday after spending more than three years behind bars, prompting outrage and condemnation from Western leaders and his supporters.

On Saturday, Navalny's mother, Lyudmila, and his lawyer were refused access to his body after arriving at the remote Siberian prison colony where he had been held, his spokeswoman Kira Yarmysh said.

"It's obvious that the killers want to cover their tracks and are therefore not handing over Alexei's body, hiding it even from his mother," Navalny's team said in a post on Telegram.

"They don't want whatever method they used to kill Alexei to come out," Yarmysh said in an online broadcast, in his backers' strongest accusation yet of foul play.

Across the country, Russian police on Saturday moved swiftly to break up small protests in honour of the Kremlin critic, arresting more than 400 people in 36 cities, the OVD-Info rights group said.

"Alexei Navalny's death is the worst thing that could happen to Russia," said one note left among the flowers at a makeshift memorial in Moscow.

Bd-pratidin English/Tanvir Raihan