Britain could help secure the release of a supertanker seized off the coast of Gibraltar if Iran provides "sufficient guarantees" that the cargo is not bound for Syria, the Foreign Secretary has said.
Jeremy Hunt says he has spoken to his Iranian counterpart Javad Zarif about the Grace 1 tanker, which was detained last week, in what he described as a "constructive call".
"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," Mr Hunt told Sky.
"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."
He added: "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."
Mr Hunt insisted that he wants the situation "de-escalated" whilst at the same time being "absolutely clear about our principles that we uphold the rule of law".
"We will not allow oil to be sent to Syria, which is a regime which uses chemical weapons against its own people.
"So what we’re seeking to do is to resolve the situation in the context of our international commitments."
It comes as the captain, chief officer and two second officers of the Iranian supertanker were conditionally bailed without charge, according to the Royal Gibraltar Police.
Their arrests come after a Royal Navy warship was forced to stop three Iranian patrol boats as they tried to stop a British tanker through the Strait of Hormuz, as a retaliation for the arrest of the Grace 1 crew.
Tensions between Tehran and London have heightened since the supertanker was stopped.
The vessel was suspected of violating EU sanctions by carrying a shipment of Iranian oil to the Baniyas refinery in Syria - with laboratory testing confirming the cargo to be 2.1 million barrels of light crude oil.
A warning was issued by Iranian President Hassan Rouhani of unspecified "repercussions" in response of the seizure.
Iran also accused Britain of playing a "dangerous game" and warned the UK will be "slapped in the face" after it seized the tanker was seized.
Tehran's threat comes as the Ministry of Defence confirmed plans to send Type 45 Destroyer HMS Duncan - one of the most advanced warships in the world - to the Gulf in the next few days.
Days later, HMS Montrose was forced to act against three patrol boats in the Strait of Hormuz as they attempted to impede the passage of BP-operated tanker British Heritage.
The Royal Navy frigate drove off the boats, which were thought to have been operated by the Iranian Revolutionary Guard - an incident they have denied.
On Friday, plans to dispatch Type 45 Destroyer HMS Duncan to the region to relieve HMS Montrose were brought forward by the Government, so that the Type 23 frigate can undergo planned maintenance and crew changes.
In London, ministers including the Foreign Secretary have urged Tehran to "de-escalate" the situation in the Gulf.
The Royal Gibraltar Police said the investigation related to the arrests is ongoing and the Grace 1 remains in detention.The crew of the Iranian supertanker stopped off the coast of Gibraltar by police and the Royal Marines have been conditionally bailed without charge.
The Royal Gibraltar Police arrested the captain, chief officer and two second officers of the Grace 1 earlier this week as a "consequence of the ongoing investigation into the suspected breach of EU sanctions on Syria”.
The crew were stopped by the Royal Marines and Gibraltar Police last Thursday, suspected of trying to deliver oil to Syria.