TEHRAN/LONDON — Iran's port authority said on Tuesday it has been in contact with British authorities as part of efforts to secure the release of a tanker seized off Gibraltar.

Gibraltar — a British overseas territory — seized the Grace 1 supertanker on July 4 with the help of British Royal Marines on suspicion it was shipping oil to Syria in violation of EU sanctions.

A court in Gibraltar is to decide the fate of the ship on Thursday, when an order for its detention lapses.

The deputy head of Iran's port authority, Jalil Eslami, said in a report by state news agency IRNA that Britain had shown an interest in overcoming the problem and documents had been exchanged.

"Efforts from Iran and the port organization have been made for the release of this ship," he was quoted as saying.

"I hope this problem will be resolved in the near future and that the ship can continue its movement with the flag of the Islamic Republic of Iran."

Gibraltar and US officials believed the tanker was destined for Syria to deliver oil, in violation of separate sets of EU and US sanctions.

Iran called the seizure of the ship "piracy" and warned it would not let the interception go unanswered.

On July 19, Iran's Revolutionary Guards impounded the British-flagged Stena Impero oil tanker in the strategic Strait of Hormuz for breaking "international maritime rules".

Meanwhile, Gibraltar said on Tuesday it was seeking to de-escalate issues.

"We continue to seek to de-escalate issues arising since the lawful detention of Grace 1," a spokesman for Gibraltar said. The current detention order on the vessel expires on Saturday night, the spokesman said. — Agencies