Russia's Victory Day military parade commemorating 80 years since the defeat of Nazi Germany started on Moscow's Red Square on Friday.

Russian President Vladimir Putin was seen sitting next to President Xi Jinping, with around two dozen other foreign leaders also attending the event.

Brazil's Luiz Inácio Lula da Silva and Venezuelan President Nicolas Maduro were among the guests, along with Serbian President Aleksandar Vucic and Slovakian Prime Minister Robert Fico, who is the only European Union leader to have travelled to Moscow for the event.

In an address, Putin said that Russia will always remember and appreciate the Allied contribution to victory in World War II.

"Russia highly appreciates the contribution to the victory of resistance fighters, Allied armies and the courageous people of China," he said.

"Russia has been and will remain an indestructible barrier against Nazism, Russophobia and anti-Semitism."

Thousands of soldiers marched in formation through Red Square, along with military vehicles and weapons.

Military units from 13 countries, including the People's Liberation Army, also took part in the parade.

Moscow was adorned in red flags and signs reading "victory" for the occasion, but there was also heavy security present in the Russian capital.

World War II is officially remembered in Russia as the "Great Patriotic War", beginning with Germany's surprise invasion of the Soviet Union in 1941.

The war had a devastating impact on the Soviet Union, resulting in more than 20 million civilian and military deaths. (Agencies)