Earlier in the day, Hunt said following phone talks with Zarif that the United Kingdom would facilitate the release of the Iranian supertanker if Tehran could guarantee it's not Syria-bound.
Zarif, in turn, stressed that Iran would continue oil exports under any circumstances and urged the United Kingdom to immediately release the supertanker, the local Mehr news agency reported, citing the foreign minister of Iran.
On July 4, the government of Gibraltar said its law enforcement agencies, assisted by Royal Marines, had detained an Iranian supertanker loaded with two million barrels of crude oil. Gibraltar Chief Minister Fabian Picardo said that his government "had reasons to believe" that the tanker was headed to the Banyas Refinery, which belongs to an entity that is subject to the EU sanctions against Syria. Iran has denied that Grace 1 transported oil to Syria.
On Saturday, the Gibraltar police said they had released on bail the four crew members, detained and interrogated earlier this week.
Spanish Foreign Minister Josep Borrell, in turn, claimed that the vessel had been detained at the request of the United States in a bid to zero Iranian oil exports.