People lined up for at least half a mile outside the Moscow church where Alexey Navalny’s funeral was taking place Friday to bid farewell to Russia’s most prominent opposition figure. Navalny, one of the most vocal critics of President Vladimir Putin, died two weeks ago in a remote Russian prison, and his family and allies have accused the Russian leader of having him killed.

There was a large police presence and fences were erected by Russian authorities around the Moscow church as Navalny’s casket arrived. Crowds chanted the opposition leader’s name. Several cars with foreign flags were seen near the church, including the German and French flags.

The Kremlin warned the public on Friday against any unsanctioned gatherings in support of Navalny.

“Just a reminder that we have a law that must be followed. Any unauthorized gatherings will be in violation of the law, and those who participate in them will be held accountable — again, in line with the current law,” Kremlin spokesman Dmitry Peskov told journalists.

Navalny, 47, died in an Arctic penal colony on Feb. 16. Prison authorities say he died of natural causes. His family fought for over a week to have his body returned to them. It was finally handed over to his mother on Saturday.