Russia on Friday held its first royal wedding since the 1917 Bolshevik revolution toppled the Romanov monarchy, with aristocrats travelling from across Europe for the lavish ceremony.

Grand Duke George Mikhailovich Romanov, 40, and his Italian fiancée Rebecca Virginia Bettarini, 39, were preparing to say their vows at Saint Isaac's cathedral in the former imperial capital Saint Petersburg in the presence of dozens of European royals.

Hundreds of foreign guests travelled to Russia's second city for the Orthodox Christian ceremony, including Queen Sofia of Spain, Prince Rudolph and Princess Tilsim of Liechtenstein, and the former king and queen of Bulgaria.

Russia was to hold its first royal wedding, on October 1, 2021, since the 1917 Bolshevik revolution toppled the Romanov monarch.

The guest list of 1,500 people included other prominent names like Konstantin Malofeyev, a monarchist and billionaire close to the Kremlin, and Russian foreign ministry spokeswoman Maria Zakharova.

Ahead of the wedding, Romanov said the couple chose to tie the knot in Saint Petersburg because it was the first place in the country where the family returned in the early 1990s.

"It is very, very close to our family," he told Saint Petersburg-based news website Fontanka ahead of the wedding.

Saint Petersburg is "the history of Russia", he added, "the history of the House of Romanov."

Born in Madrid, Romanov is the son of Grand Duchess Maria Vladimirovna Romanova, the self-proclaimed heir to Russia's imperial throne. 

She is the granddaughter of Grand Duke Kirill, a cousin of Nicholas II, the last Russian tsar who was executed along with his wife Alexandra and five children by the Bolsheviks in 1918.

Passing by Saint Isaac's cathedral on Friday, Galina Bobrova said she wished the soon-to-be newlyweds "happiness".

"For us, the monarchy is something from a past life, of course, but it's interesting," the 50-year-old told AFP.

'Ambassadors of goodwill'

The last wedding in Russia of an heir to the Romanovs was that of Nicholas II and Alexandra, 127 years ago.

Buried after their execution in a place long kept secret by the Soviet authorities, their bodies and those of their children were transferred in 1998 to the Peter and Paul Cathedral in Saint Petersburg. 

Grand Duchess Maria Vladimirovna of Russia (right), a mother of Grand Duke George Mikhailovich Romanov (left) congratulates Victoria Romanovna Bettarini during their wedding ceremony.

The family was canonised by the Orthodox Church in 2000 as martyrs.

Romanov, who graduated from Oxford and spent much of his life in France, met Bettarini in Brussels, where he worked in the European Parliament. He also held jobs at Russian mining giant Norilsk Nickel.

Bettarini converted to the Orthodox faith last year and took the name Victoria Romanovna. Her wedding dress Friday featured the coat of arms of the Russian Empire, embroidered in gold. 

The couple moved to Russia three years ago, settling first in the Moscow suburbs before relocating to the city centre next to the Kremlin. 

Romanov now works on several charity projects.

He said he believes European and Russian royals could help Moscow and the West mend fraying ties. 

Grand Duke George Mikhailovich Romanov and Victoria Romanovna Bettarini leave the Saint Isaac's Cathedral as Russian honour guards salute them during their wedding ceremony.

"I think that we can be ambassadors of goodwill."

But President Vladimir Putin's spokesman on Friday poured cold water on the idea that Romanov would become a player in Russian political life.

"The president does not plan to congratulate the newlyweds," Dmitry Peskov told reporters. "This marriage does not belong on our agenda in any way."