Press TV - Iran�s Foreign Ministry has for the third time over the past few days hosted the UK ambassador to demand answers over the seizure of an Iranian supertanker by British forces in Gibraltar last week.

Foreign Ministry spokesman Abbas Mousavi said Monday morning that Robert Macaire was not officially summoned as the two sides had agreed to discuss the issue "within the framework of preplanned meetings" that he routinely holds with Iranian officials.

Early last Thursday, British Royal Marines in Gibraltar stormed the Panama-registered 300,000-tonne Grace 1 vessel and detained it, alleging that it was carrying Iranian crude oil to Syria in possible violation of the European Union�s sanctions on the war-torn Arab country, a claim Iran has denied.

Iran summoned the British ambassador on Thursday afternoon to formally protest against the provocative incident, condemning it as a �form of piracy.�

At the time, the ministry provided the British envoy with the documents relating to the supertanker and its cargo, indicating the full legalization of the vessel, insisting that Iran would use all of its political and legal capacities to release the tanker and vindicate the country�s rights.

According to Iranian Deputy Foreign Minister Abbas Araghchi, Macaire was also present at the foreign ministry on Sunday over the issue and was shown documentation that confirmed the tanker was not headed for Syria.

Gibraltar authorities say Grace 1's 28 crew members -- nationals of India, Pakistan and Ukraine -- are currently staying aboard the tanker, along with local police and customs officers boarding the vessel for the duration of a probe. On Friday, Gibraltar extended the tanker's detention for 14 days.

On Friday, Secretary of Iran�s Expediency Council Mohsen Rezaei called for the reciprocal seizure of a British oil tanker in case London refused to release the vessel.

Separately on Friday, Spain�s acting Foreign Minister Josep Borrell said on Friday that Madrid was planning to lodge a formal complaint against the UK and was studying the circumstances and looking at how the incident is affecting its sovereignty.

Spain, which challenges the British ownership of Gibraltar, has said the seizure was prompted by a US request to Britain and appeared to have taken place in Spanish waters.

However, Gibraltar rejected the claim, saying it had acted independently.

The seizure of Grace 1 comes as the US has pledged to cut Iran�s oil exports to �zero� as part of the sanctions that it has reinstated after leaving a landmark multilateral 2015 nuclear deal with Iran in May last year.

Tensions further heightened between Washington and Tehran when the US deployed military reinforcements and troops to the Middle East in early May, citing alleged �threats� from Iran.

Several oil tankers have also been targeted near the Persian Gulf region, with Washington and its ally Saudi Arabia quickly blaming Iran for the suspicious attacks. Tehran has rejected any involvement, saying the incidents appear to be false flags meant to frame the Islamic Republic.