Russians pay tribute to victims of political repression

STORY: Ambassadors of Britain, France and Poland as well as the U.S. embassy Charge d'Affaires were among those who took part at the event in the city center.

Nearly 700,000 people were executed in USSR during the Great Terror of 1937-38, according to conservative official estimates.

Leader Joseph Stalin was repudiated by the Soviet Union after his death. He was recognized as responsible for the deaths of millions of Soviet citizens.

Memorial, Russia's best-known human rights group, was ordered to be dissolved last December for breaking a law requiring certain civil society groups to register as foreign agents, capping a year of crackdowns on Kremlin critics the likes of which had not been seen since Soviet days.