Moscow, Feb. 18 -- The hundreds of flowers and candles laid in Moscow on Friday to honour the memory of Alexei Navalny, Russia's most prominent opposition leader, were taken away overnight in black bags.

Russia's prison service said that Navalny, 47, fell unconscious and died on Friday after a walk at the "Polar Wolf" Arctic penal colony. Navalny's spokeswoman Kira Yarmysh on Saturday confirmed his death, citing an official notice given to his mother, Lydumila.

In central Moscow, several dozen roses and carnations remained in the softening snow on Saturday at the monument to the victims of Soviet repression, which sits in the shadow of the former KGB headquarters on Lubyanka Square.

Vladimir Nikitin, 36, was alone laying a carnation at...