Iran demands return of tanker as UK sends second frigate to Gulf

Iran demanded the UK release an oil tanker seized in Gibraltar last week and warned Britain was playing a “dangerous game” as the Royal Navy prepared to send a second warship to the region.

The supertanker Grace 1 was seized by Royal Marines on suspicion of EU sanctions busting by taking oil to Syria. The UK maintains the vessel was in its waters when boarded.

Iranian foreign ministry spokesman Abbas Mousavi challenged the UK's assertion, telling the IRNA news agency “the legal pretexts for the capture are not valid [...] The release of the tanker is in all countries’ interests”.

“Such illegal measures could increase tensions in the Persian Gulf,” he said.

The Gulf state has warned it would take retaliate if the tanker was not released. Oil prices spiked as tensions rise in the region.

On Thursday, Britain accused Iran of sending three vessels to block the BP–owned vessel British Heritage from passing through the strait of Hormuz. The attempt was thwarted when the Royal Navy frigate HMS Montrose confronted the Iranian boats.

The government on Friday said it was accelerating plans to send a second warship to the Gulf. HMS Duncan, currently in the Mediterranean, was expected to join the Montrose in the region next week.

"As part of our long-standing presence in the Gulf, HMS Duncan is deploying to the region to ensure we maintain a continuous maritime security presence while HMS Montrose comes off task for pre-planned maintenance and crew changeover,” a government spokesman said.

"This will ensure that the UK, alongside international partners, can continue to support freedom of navigation for vessels transiting through this vital shipping lane."

Mousavi also called on foreign powers to “leave the region because Iran and other regional countries are capable of securing the regional security”.

British ships operating in the Gulf, a key waterway for the flow of oil from the Middle East to the rest of the world, have been put on the highest state of alert amid fears that commercial vessels are vulnerable to attack by Iranian gunboats.

Meanwhile, in London, Foreign Secretary Jeremy Hunt, vying to be the UK's next prime minister, took the opportunity to use the crisis to say he would increase spending on the Royal Navy.

Hunt promised to reverse cuts to the size of the Royal Navy if he became prime minister.