Three improvised explosive devices were thrown at the Russian consulate in the southern French port city of Marseille on Monday but no one was injured, a police source said.

Only two of the devices detonated in the attack on the third anniversary of Russia's campaign in Ukraine, the source said.

The consulate was sealed off by police and AFP journalists heard a detonation caused by a bomb disposal robot.

The Russian foreign ministry denounced what it called a "terrorist attack".

"The explosions on the territory of the Russian consulate general in Marseille have all the signs of a terrorist attack," foreign ministry spokeswoman Maria Zakharova told Russian reporters.

"We demand that the host country undertake exhaustive and speedy investigative measures, as well as steps to strengthen the security of Russia's foreign missions," said Zakharova.

Paris condemned the incident. "France condemns any infringement of the security of diplomatic compounds," a foreign ministry spokesperson told reporters.

"The inviolability, protection and integrity of diplomatic and consular compounds and their staff are fundamental principles in international law," the spokesperson said.

A dozen leaders from Europe and Canada were in Ukraine's capital on Monday to mark the third anniversary of Russia’s military campaign.

The visitors, including European Commission President Ursula von der Leyen and Canadian Prime Minister Justin Trudeau, were set to attend anniversary events and discuss supporting Kyiv with President Volodymyr Zelenskyy. (Agencies)