The Danish Maritime Authority said Thursday it had decided to hold a container ship arriving from Saint Petersburg, citing a lack of proper registration.

“The vessel is being held on the grounds that it is not properly registered,” the authority told AFP in an email.

“The ship had declared that it was sailing under the flag of the Comoros. The Comoros informed the Maritime Authority that the vessel was not listed in their register,” it added.

Danish media has identified the ship as the Iranian-flagged Nora, the vessel anchored just north of Denmark, in the Kattegat strait.

According to data from the maritime tracking website VesselFinder, it left Saint Petersburg on January 16, bound for Egypt.

According to broadcaster TV2, the ship, which was previously named Cerus, is subject to US sanctions.

The ship is reportedly part of an Iranian fleet of ships controlled, according to US authorities, by Mohammad Hossein Shamkhani — son of Ali Shamkhani, a top political advisor to Iran’s supreme leader Ayatollah Ali Khamenei.