An Iranian tanker seized by Gibraltar last month is preparing to set sail after being released, a senior Iranian shipping official said yesterday.

The ship’s seizure on July 4, with the help of British Royal Marines, triggered a sharp deterioration in relations between Tehran and London and the tit-for-tat detention by Iran of the British-flagged tanker Stena Impero.

The Grace 1 will be renamed and switch to the Iranian flag for its onward journey, the deputy head of Iran’s Ports and Maritime Organisation, Jalil Eslami, told state television.

“At the owner’s request, the Grace 1 will depart for the Mediterranean after being reflagged under the Islamic Republic of Iran’s flag and renamed as Adrian Darya for the voyage,” Eslami said.

“The ship was of Russian origin and Panama-flagged and is carrying two million barrels of Iranian oil,” he added.

Gibraltar’s Supreme Court ordered the tanker released on Thursday after the British overseas territory said it had received assurances from Iran that the Grace 1 would not head to any country subject to European Union sanctions.

The vessel had been detained on suspicion that its cargo was destined for the Banyas oil refinery in Syria in breach of an EU embargo.

But Iran denied it had provided any assurances to secure the ship’s release, saying Gibraltar was only seeking to “save face”.