Face of Nation : Foreign Secretary Jeremy Hunt and Iranian foreign minister Mohammad Javad Zarif discussed the crisis and heightened tensions in a phone call.
In a series of tweets announcing the conversation about Grace 1, Mr Hunt said it had been a “constructive call”.
He wrote: “I reassured him our concern was destination not origin of the oil on Grace One & that UK would facilitate release if we received guarantees that it would not be going to Syria, following due process in Gib courts.”
He later told Sky News: “I made it clear that we want to resolve the situation with the Grace 1 tanker in Gibraltar. Our concern has always been the destination of the tanker and the fact that it was taking oil to Syria – not the origin of the oil.
“And I said that if we could receive sufficient guarantees that that tanker was not headed for Syria then we would be able to resolve the situation, following of course due process in the Gibraltar courts.
“Foreign minister Zarif reassured me that Iran too wanted to resolve the situation, and I have also spoken to the chief minister of Gibraltar, Fabian Picardo, and they are working very closely with us to try and resolve the situation.”
It comes after the supertanker’s crew members, who were arrested off the coast of Gibraltar, were conditionally bailed without charge.
The ship was seized last week in an operation involving British Royal Marines, after it was suspected of taking crude oil to Syrian president Bashar al Assad’s regime in breach of EU sanctions.
Royal Gibraltar Police arrested the captain and his deputy on Thursday, while two second officers of the Grace 1 tanker were held on Friday.
The arrest of the four men, who are Indian nationals, came after a Royal Navy warship drove away Iranian patrol boats attempting to impede the progress of a British tanker through the Strait of Hormuz.
Police have said the investigation related to the arrests was ongoing and the vessel remained in detention.
Iran previously demanded the immediate release of its oil tanker captured off the coast of Gibraltar, warning the UK: “This is a dangerous game and has consequences.”
A senior Iranian cleric, Kazem Sedighi, also warned Britain would soon be “slapped in the face” for “daring” to capture the Iranian supertanker Grace 1.
The UK later said it would increase its military presence in the Gulf by sending a second warship to the region.
The vessel will operate alongside the Royal Navy frigate HMS Montrose, and US allies in the Gulf, but she will not be part of an international maritime coalition proposed by Washington.
It is understood that HMS Duncan was always due to travel to the region to give additional relief to HMS Montrose.
However, her deployment has been brought forward as a result of the deepening crisis with Iran.
