In the early hours of Thursday morning Gibraltar Port and law enforcement agencies, with the assistance of a detachment of Royal Marines, boarded a supertanker and detained the ship and its crew for allegedly transporting crude oil to Syria and thereby contravening EU sanctions.
The Gibraltar government was responding to information that the Panama-registered ship, Grace 1, was heading for the Banyas refinery in Syria. That refinery is the property of an entity that is subject to European Union sanctions against Syria.
In a video and written statement early on Thursday morning, announcing that the ship had been detained, chief minister Fabian Picardo said: "Yesterday we published Regulations and a Notice to enforce those sanctions against this vessel and its cargo.
"I also gave a Direction requiring the Captain of the Port, assisted by the Royal Gibraltar Police and Her Majesty's Customs, to take control of the Grace 1.
"With my consent, our Port and Law Enforcement agencies sought the assistance of the Royal Marines in carrying out this operation.
"As the sanctions being enforced are established by the EU, I have written this morning to the Presidents of the European Commission and Council, setting out the details of the sanctions which we have enforced.
"I want to thank the brave men and women of the Royal Marines, the Royal Gibraltar Police, Her Majesty's Customs Gibraltar and the Gibraltar Port Authority, for their work in securing the detention of this vessel and its cargo.
"Be assured that Gibraltar remains safe, secure and committed to the international, rules-based, legal order."
Although the official statement did not reveal where Grace 1 had collected the crude oil, it is believed to have been from Iran.