Iran's oil tanker Grace 1, which was seized by Gibraltar, "will be freed in the very near future," local media reported on Tuesday citing the country's Deputy Head of Iran's Ports and Maritime Organization (PMO) for Maritime Affairs.

The Grace 1 supertanker, carrying 2.1 million barrels of oil, was intercepted by British Royal Marines and Gibraltar's police on July 4 as it transited through waters claimed by Gibraltar, which is located on Spain's southern tip.  

Earlier, Gibraltar's supreme court granted a 30-day extension to allow authorities to detain the Iranian oil tanker Grace 1 until August 15, the Gibraltar Chronicle newspaper said. 

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 U.S. officials believed the tanker was destined for Syria to deliver oil, in violation of separate sets of EU and U.S. 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."

(With input from AFP)