Navalny's funeral in pictures: Mourners gather in Moscow as riot police contain crowds

Crowds gathered in Moscow on Friday to observe Alexei Navalny's funeral, with allies of the deceased Russian opposition politician saying over 1,000 people had congregated.

CNBC could not independently verify the number.

Remains of snow clutched to the streets in a grey Moscow, as people lined up outside the church where the memorial service is set to take place. Heavy police presence is expected, as political tensions run high ahead of presidential elections due to take place over March 15-17.

Kremlin spokesperson Dmitry Peskov on Friday said that any unsanctioned gatherings in support of Navalny would be against the law, according to a NBC News translation.

Navalny died under unclear circumstances last month while serving a sentence in an arctic prison colony. Reports say the death certificate pointed to "natural causes."

Navalny's family, supporters and Western leaders have said Russian President Vladimir Putin is responsible for his rival's death, but the Kremlin has denied any involvement.

Here's a look at the memorial as it unfolded.