SIMIC

The cargo vessel transporting cars, which was headed for St Petersburg, is "strongly suspected of being linked to Russian interests targeted by the sanctions", said Capt Veronique Magnin, of the French Maritime Prefecture.

The ship, the Baltic Leader, was diverted to the port of Boulogne-sur-Mer in northern France Capt Magnin said, adding that checks were being carried out by customs officials and that the ship's crew was "being cooperative".

The US Treasury Department has issued blocking sanctions against the vessel saying it was owned by a subsidiary of Russian lender Promsvyazbank, one of the Russian entities hit by US sanctions.

The bank's CEO, Pyotr Fradkov, is the son of Mikhail Fradkov, a former head of Russia's foreign intelligence service, who also served as prime minister under Vladimir Putin. Pyotr Fradkov was himself included in the latest round of US sanctions.

Promsvyazbank, in a comment sent to Reuters, said its subsidiary no longer owns the Baltic Leader, and that it was bought by a different entity before the sanctions were imposed.

The Russian embassy in France is seeking an explanation from authorities over the seizure, Russia's RIA news agency quoted the embassy as saying. The embassy also said the ship's crew had been allowed to come ashore and move freely about the port.

The United States, European Union, and other Western states this week imposed extensive new financial and trade sanctions on Russia after it sent military forces into neighbouring Ukraine.

The US Treasury said Promsvyazbank was put under sanctions "for operating or having operated in the defence and related materiel and financial services sectors of the Russian Federation economy". It was also targeted by EU sanctions.