US Ambassador to Russia Lynn Tracy announced that he visited a makeshift memorial dedicated to Russian opposition leader Alexei Navalny in Moscow today, as Russian authorities crack down on such gatherings after his death in prison was announced on Friday.

“Today, at the Solovetsky stone, we mourn the death of Alexei Navalny and other victims of political repression in Russia”the US embassy wrote on its Telegram account.

This message was accompanied by a photo of the ambassador in front of several bouquets of flowers that had been placed at this memorial to the victims of political repression, which is located right next to Lubyanka, the headquarters of the Soviet KGB and then the Russian FSB.

“We extend our sincerest condolences to his family, colleagues and supporters Alexei Navalny. His strength was an inspiring example. We honor his memory,” the US embassy said.

Despite the crackdown and warnings, hundreds of Russians took part in small rallies in various cities to pay tribute to Alexei Navalny, a well-known critic of the Kremlin who died aged 47 in a prison in the Russian Arctic.

Russian authorities made more than 400 arrests on Friday and Saturday during rallies held in 36 cities, with the majority of arrests taking place in St. Petersburg and Moscow, according to specialist NGO OVD-Info.

Today, protective railings were placed around the perimeter of another monument in the Russian capital, the “Mourning Wall”, an AFP journalist found.

Dozens of police officers are stationed there, but some people have been allowed to approach the memorial to leave flowers.

The death of Alexei Navalny, about which the Kremlin is keeping a fishy silence, has caused a wave of outrage in Western countries, many of which blame Russia.

Leonid Volkov, an ally of Navalny, said today that it was “not a death, but an assassination”.

He called on Alexei Navalny’s supporters to “not be discouraged”. “That’s what they expect from us now. What he dedicated his life to must win.”