Iran’s military on Tuesday pledged to retaliate against the seizure by British Royal Marines of an oil tanker off the coast of Gibraltar last week.
“Capture of the Iranian oil tanker based on fabricated excuses will not be unanswered and when necessary Tehran will give an appropriate answer,” said Maj Gen Mohammad Bagheri, Iran’s armed forces chief of staff.
The marines boarded the Grace 1 off the coast of Gibraltar on Thursday and seized it for breaking sanctions by taking oil to Syria.
Iran has demanded the immediate release of the vessel, while the Islamic Revolutionary Guard Corps commander threatened on Friday to seize a British ship in retaliation.
“It will be reciprocated, at a suitable time and in a suitable place,” Maj Gen Bagheri, told the official Irna news agency.
The warning highlights mounting risks to shipping in a region that exports about a third of all seaborne petroleum.
BP is keeping an oil carrier empty close to Saudi Arabia, rather than risk it being seized by Iran.
The British Heritage, which can haul about 1 million barrels of oil, was sailing toward Iraq's Basra terminal in the south of country.
It made an abrupt U-turn on Saturday over BP’s concerns.
Meanwhile, investigations into Iran’s seized vessel have revealed that the supertanker was fully loaded with crude oil.
"Gibraltar can now confirm, after having received the results of comprehensive laboratory testing, that the Grace 1, which was detained in the early hours of Thursday morning, is loaded to capacity with crude oil," its government said.
“The results of these tests contradict the statements of some commentators from outside who had speculated that the cargo on the vessel was not crude.”
The government said the Grace 1 was detained when it sailed into British Gibraltar's territory, having left the international waters of the Straits of Gibraltar on an arranged call for provisions and spare parts.
Spain, which challenges UK ownership of Gibraltar, had said last week that the action was prompted by a US request to Britain and appeared to have happened in Spanish waters.
Gibraltar said the vessel was detained because it was suspected to be heading for Baniyas refinery in Tartous, which is owned by Baniyas Oil Refinery Company and subject to EU sanctions.
Legal experts say the EU sanctions only explicitly prohibit the export of jet fuel to Syria, although a sale to anyone who is designated as subject to sanctions would be in breach of the regulations.
The Gibraltar authorities did not disclose the origin of the oil, although officials in Tehran have said it was an Iranian tanker.
Iran said the tanker was in international waters, not headed to Syria, and described the UK’s actions as piracy.
Six tankers have been attacked since early May and the US blamed Iran for the incidents, which Tehran denies.
Insurance costs soared after the attacks and some owners initially became wary of sailing to the region.
Tension escalated since the US withdrew from an international nuclear accord with Iran then resumed sanctions against it.
