The Grace 1 vessel was halted in the early hours of Thursday by Gibraltar police and customs agencies Gibraltar is a British overseas territory, a small rocky outcrop on Spain’s southern tip MADRID: A supertanker suspected of carrying crude oil to Syria in violation of EU sanctions was detained in Gibraltar on Thursday, the territory’s Chief Minister Fabian Picardo said. The Grace 1 vessel was halted in the early hours of Thursday by Gibraltar police and customs agencies, aided by a detachment of British Royal Marines. “We have reason to believe that the ‘Grace 1’ was carrying its shipment of crude oil to the Banyas Refinery in Syria,” Picardo said in a statement. “That refinery is the property of an entity that is subject to European Union sanctions against Syria.” The Grace 1 is a Panamanian-flagged tanker, according to the shipping trade publication Lloyd’s List. “We have detained the vessel and its cargo,” Picardo said. Spain"s caretaker foreign minister Josep Borrell said the tanker was stopped by British authorities after a request from the United States. The EU and others have imposed sanctions on Assad"s government over its continued crackdown against civilians. They currently target 270 people and 70 entities. Britain welcomed on Thursday the "firm actions" by Gibraltar to detain The Grace 1 on suspicion of carrying crude oil to Syria, saying the move sent a clear message that the violation of EU sanctions was unacceptable. "We welcome this firm action to enforce EU sanctions against the Syrian regime and commend those Gibraltarian authorities involved in successfully carrying out this morning"s operation," Prime Minister Theresa May"s spokesman said. "This sends a clear message that violation of the sanctions is unacceptable." Meanwhile, Iran summoned the British ambassador in Tehran over the "illegal seizure" of an Iranian oil tanker in Gibraltar on Thursday, Iranian state TV quoted Foreign Ministry spokesman Abbas Mousavi as saying. The EU has imposed sanctions on 277 Syrian officials including government ministers over their role in the “violent repression” of civilians. It has frozen the assets of some 72 entities and introduced an embargo on Syrian oil, investment restrictions and a freeze on Syrian central bank assets within the European Union. Gibraltar is a British overseas territory, a small rocky outcrop on Spain’s southern tip.