Iran told freed tanker must not go to Syria
Britain has insisted Iran must abide by its assurances that a supertanker will not proceed to Syria following its release by Gibraltar.
Officials in the British Overseas Territory have allowed the Grace 1 to leave, despite a last-minute US attempt to seize the vessel.
It was seized on July 4 in a Royal Navy operation off Gibraltar after it was suspected of carrying oil to Syria in breach of European Union sanctions.
The British-flagged oil tanker Stena Impero was later seized by Iranian forces and remains held by the Islamic Republic.
The Foreign Office said it noted the steps taken by Gibraltar to prevent the Grace 1's cargo from reaching Syria, adding there is "no comparison or linkage" between the "illegal seizure" of commercial shipping vessels in the Strait of Hormuz and the enforcement of EU sanctions.
Foreign Office minister Andrew Murrison said: "I hope very much that the written assurances that Iran has given about the destiny of Grace 1 will be supported and that we will not end up with Grace 1 ending up in an entity that has been the subject of sanctions by the European Union.
"We would want to hold Iran to that and ensure that indeed Grace 1 does not end up supplying (Syria President) Bashar al-Assad's regime."
The Supreme Court in Gibraltar had delayed a decision to release the Grace 1 after the US Department of Justice made an application to extend the vessel's detention, the Gibraltar government said earlier yesterday.
But the Gibraltar Chronicle reported there was no US application before the court when the hearing resumed yesterday afternoon and so the vessel was allowed to leave.
A Foreign Office spokesman said: "The UK notes the conclusion of Gibraltar's legal proceedings and the steps Gibraltar's authorities have taken to prevent the ship's cargo from reaching Syria in contravention of EU Syria sanctions.
"We note the Government of Gibraltar has received assurances from Iran that the Grace 1 will not proceed to Syria.
"Iran must abide by the assurances they have provided.
"We will not stand by and allow Iran - or anyone - to bypass vital EU sanctions on a regime that has deployed chemical weapons against its own people.
"There is no comparison or linkage between Iran's unacceptable and illegal seizure of, and attacks on, commercial shipping vessels in the Strait of Hormuz and the enforcement of EU Syria sanctions by the Government of Gibraltar. Freedom of navigation for commercial shipping must be respected and international law upheld."
In recent weeks the Persian Gulf region has seen six attacks on oil tankers that the US has blamed on Iran and the downing of a US surveillance drone by Iranian forces.