Russians traveled from far and wide to bear witness as Aleksei A. Navalny, the Russian opposition leader who died in an Arctic prison at 47, was buried in Moscow on Friday amid a heavy police presence.

Some mourners chanted his name. Others said, “Thank you for your son!” to Mr. Navalny’s mother, Lyudmila Navalnaya, who had fought for days to reclaim his body. Eventually, the authorities relented, but Mr. Navalny’s team described having to overcome a gantlet to persuade a church, a cemetery and a hearse to take part in the burial.

Thousands turned out for the service, Mr. Navalny’s supporters estimated. Foreign diplomats were among the crowd. Some Russians shouted, “No to war,” risking arrest. Mr. Navalny’s coffin was lowered into the cemetery grounds to the strains of the Sinatra song “My Way” and one from the movie “Terminator 2,” video showed.

Mourners walking to the Borisovskoye Cemetery on Friday in Moscow during the funeral for Mr. Navalny, who died in an Arctic prison camp, above. Law enforcement officers detained a man near the cemetery, below.

Carrying Mr. Navalny’s coffin from the Moscow church where his funeral was held on Friday.

Laying flowers at the grave in Moscow.

A journalist estimated in a Facebook post that “tens of thousands” of people had assembled for the funeral, though that figure could not be verified.

Diplomats, including the French ambassador to Russia, Pierre Levy, second from left, and the U.S. ambassador, Lynne M. Tracy, second from right, waiting near the church for the service.

Police officers standing on the roof of an apartment building during the burial.

The police presence outside the cemetery where the burial was taking place.

Some people chanted Mr. Navalny’s name and thanked his mother for her son.

Law enforcement officers outside the Mother of church after Mr. Navalny’s funeral.

Videos showed the crowd tossing flowers onto the road as the funeral cortège left the church for the cemetery.

Valerie Hopkins contributed reporting.