The Shtandart arrived in La Rochelle, on the southwest coast, to replenish supplies and refuel from Monday to Tuesday, said the source, asking not to be named. Russian ships are generally banned from entering EU ports due to the sanctions.

The 34-metre-long (112 feet) three-masted ship, built in 1999 and an exact replica of a frigate belonging to Tsar Peter the Great, was barred from entering Brest and from taking part in the Breton port's maritime festival in July.

But the prefecture of the Charente-Maritime region allowed the vessel to make the stop in La Rochelle.

"(The Shtandart) arrived on Monday morning and left on Tuesday afternoon," said the source, specifying that it was not clear where the boat was headed next.

Contacted by AFP, the Charente-Maritime prefecture did not immediately comment. A source close to the authorities indicated that it was only a "technical stopover" and that there was no reason to prohibit it.

In a video published Tuesday on the boat's Instagram account, its captain and owner Vladimir Martus was filmed commenting on the stopover.

"Shtandart is going to depart from La Rochelle. It's been beautiful to be here, we've got fuel, we got food, we sent the crew to shower, we are going to sail for a week. Bye-bye La Rochelle! Hope to be here again," he said in English.

The boat was once a favourite of European maritime festivals and used extensively for cruises and training.

It has over the last 25 years taken 10,000 people aboard and participated in 200 maritime festivals.

Its ban from the Brest festival came after the regional Finistere prefecture ruled that EU sanctions against Russia included "historic ships" that had a Russian flag before the February 2022 invasion.

The vessel changed its flag in June and now is registered in the Pacific Cook Islands.

Critics have accused Martus of being connected to President Vladimir Putin's government but he contested the Finistere ruling, saying he had "no link" with Putin's administration.