A supertanker suspected of transporting oil to Syria in violation of EU sanctions was detained by British marines on Thursday off the coast of the British territory of Gibraltar.

The Grace 1 tanker was detained for trying to take oil to Syria in violation of European Union sanctions, a spokesman for the British territory said on Friday.

The crew of the tanker were being interviewed as witnesses, the spokesman said, in order to establish the nature of the cargo and its ultimate destination. Most of the crew were Indian and Pakistani nationals. Police and customs officials have remained on board.

Shipping intelligence publication Lloyd's List had been tracking the ship and the Panamanian-flagged tanker is thought to have been transporting crude oil from Iran and may have been headed for the Banyas Refinery in Syria.

Read more: German firms sent weapons-grade chemicals to Syria despite sanctions — report

"That refinery is the property of an entity that is subject to European Union sanctions against Syria," said Gibraltar's chief minister, Fabian Picardo. The refinery is a Syrian government-owned facility controlled by Syrian President Bashar Assad, and falls under the EU's Syrian Sanctions Regime.

The vessel, named Grace 1, was boarded in the early morning hours Thursday 4 kilometers (2.5 miles) off the Gibraltar coast, after it slowed down in a designated area used to ferry goods on board ships.

A British navy patrol vessel has been guarding the Grace 1 in Gibraltar

Iran demands immediate release

Iran demanded the immediate release of the tanker on Friday and the foreign ministry described the UK move as "unacceptable" in a statement.

The UK ambassador in Tehran had been summoned to a meeting on Thursday to hear a formal protest as the ministry "called for the immediate release of the oil tanker, given that it has been seized at the request of the US, based on the information currently available," the statement added.

White House national security adviser John Bolton had applauded the UK move: "Excellent news: UK has detained the supertanker Grace I laden with Iranian oil bound for Syria in violation of EU sanctions," he wrote on Twitter.

Read more: Hunting Bashar Assad's henchmen in Syria

Syria's homemade oil refineries Poisoned farmlands Plumes of black smoke rise up above the main road leading into the village of Msheirfeh in Syria's north east. Dozens of makeshift open-air refineries have sprung up here since the civil war began in 2011, as desperate locals turn to black gold to make a living. The conflict has changed the agricultural region irrevocably.

Syria's homemade oil refineries Need for black gold Most of the government-owned oil refineries have either been destroyed or taken over by militant groups. Demand for fuel is soaring, and the DIY roadside refinery industry is booming. But primitive techniques mean toxic gases are being released into the air, and leaking oil has contaminated soil and groundwater.

Syria's homemade oil refineries Barely breaking even The workers produce oil, petrol and gas for the farming population caught in the middle of the conflict. Once the oil has been refined, it's poured into used petrol containers, ready to be sold. The men make around $33 (24 euros) per barrel.

Syria's homemade oil refineries Risky situation The job is a dangerous one - the workers often fall ill, or can even be killed during the refining process. Fumes from the burning crude oil hang in the air, and explosions are frequent. Many suffer from skin rashes, burns, poison-related amputations, breathing difficulties, headaches, persistent coughs or eye infections.

Syria's homemade oil refineries Guns and oil Standing beside a pond of freshly-refined petrol, the worker on the left says he has trouble sleeping, "not because of the gun fighting in the plains, but because my body is itchy and I have had a lot of discomfort since I began working here."

Syria's homemade oil refineries Oil, oil everywhere The improvised refineries are often run by two people - usually relatives - who buy crude oil from Islamic armed forces in the Deir ez-Zor province. Many of the men wear rubber boots, as well as scarves to protect their faces. But this doesn't stop the black oil from staining their clothes, hair and skin. Breathing in toxic fumes, and getting burns and cuts, are daily realities here.

Syria's homemade oil refineries World turned upside down Before the war, many of these workers had other jobs. They were university students, farmers, public servants and school teachers, who were forced to find another way to make a living. Former farmer Nu'man Uthman, above, now runs this open-air refinery with his eldest son, Sherif.

Syria's homemade oil refineries Life before the civil war This former teacher had to leave the school where he worked when the war broke out. Now, stoking the fire underneath his refinery, he reflects: "I miss being a teacher because I was useful to others. But in this job, I feel as useless as you could possibly think." Author: Rozh Ahmad, Syria



Oil from Iran?

Agence France-Presse reported that analysts at Lloyd's List said the ship had been loaded with oil off the coast of Iran in April and made a slow journey around the Cape of Good Hope en route to the Strait of Gibraltar.

Experts said the tanker had not been sending geographic signals while in Iranian waters.

Iran has provided military support to Assad, including credit lines for oil. However, this aid has largely been choked off by renewed US sanctions. The EU issued sanctions against the regime of Syria's Assad in 2011.

Read more: EU mechanism for trade with Iran 'now operational'

If the tanker is confirmed to have been carrying Iranian oil, it would come at a difficult time in EU-Iran relations, as the block weighs a response to Iran's defiance of the faltering 2015 nuclear deal.

The EU has tried to maintain neutrality as tensions between the US and Iran have grown over US sanctions designed to bar all oil exports. Carrying Iranian oil to Syria would violate both EU and US sanctions.

Read more: How Trump's sanctions are crippling Iran's economy

A British-Spanish diplomatic spat?

On Thursday, a British Foreign Office spokesperson said: "We welcome this firm action by the Gibraltarian authorities, acting to enforce the EU Syria Sanctions regime."

The European Commission said Thursday that it had no information on the case, and that implementing sanctions was a matter for the member states.

Read more: Gibraltar between rock and a hard place on Brexit

Josep Borrell, Spain's acting foreign minister, said that he was looking into how the seizure affects Spanish sovereignty, as he claims it seems to have taken place in Spanish waters.

Borrell was reported to have said that Gibraltar has detained the ship on the request of the US.

Gibraltar is located on the Mediterranean Sea at the southern the tip of the Iberian Peninsula, and Spain does not recognize the waters around the territory as British.

wmr/jm (AFP, dpa, Reuters, AP)

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