Gibraltar, which has detained an Iranian tanker suspected of carrying oil to Syria in violation of sanctions, said Friday it acted of its own accord and not on any other government order.
Spain's Foreign Minister Josep Borrell had said the ship was detained in waters off the overseas British territory on Spain's southern tip at the request of the United States.
"There has been no political request at any time from any government," Gibraltar's government said in a statement.
"The decisions of Her Majesty's Government of Gibraltar were taken totally independently, based on breaches of existing law and not at all based on extraneous political considerations."