Iran’s top leader has said his country will retaliate over the seizure of an Iranian tanker by British authorities.

Ayatollah Ali Khamenei called the seizure of the ship “piracy” in a televised speech, saying: “God willing, the Islamic Republic and its committed forces will not leave this evilness without a response.”

The supertanker Grace 1
The supertanker Grace 1 (MoD/PA)

The Iranian supertanker, carrying 2.1 million barrels of light crude oil, was seized with the help of British Royal Marines earlier this month off Gibraltar.

Foreign Secretary Jeremy Hunt said on Saturday that Britain will facilitate the release of the ship if Iran can provide guarantees the vessel will not breach European sanctions on oil shipments to Syria.

Tensions have soared in the Persian Gulf over the past year as the Trump administration in the US has ramped up sanctions on Iran after withdrawing from Iran’s 2015 nuclear deal with world powers.