DUBAI — Iran called on Britain on Friday to immediately release an oil tanker that British Royal Marines seized last week on suspicion it was breaking European sanctions by taking oil to Syria, a foreign ministry spokesman told state news agency IRNA.

"This is a dangerous game and has consequences ... the legal pretexts for the capture are not valid ... the release of the tanker is in all countries' interest," the spokesman, Abbas Mousavi, said.

Iran has warned of reciprocal measures if the tanker is not released.

Britain said on Thursday that three Iranian vessels tried to block a British-owned tanker passing through the Strait of Hormuz, which controls the flow of Middle East oil to the world, but backed off when confronted by a Royal Navy warship.

Iran denied that its vessels had done any such thing.

Tension between Iran and the West has increased a week after Britain seized the tanker and London said the British Heritage, operated by oil company BP, had been approached in the strait between Iran and the Arabian peninsula.

Mousavi accused Britain of seizing the tanker under US pressure. "Such illegal measures could increase tensions in the Gulf," he told IRNA.

The capture of the Iranian tanker comes at a time of sharply increased US-Iranian confrontation in recent weeks. Washington has also dispatched extra troops to the region to counter what it describes as Iranian threats.

"Foreign powers should leave the region because Iran and other regional countries are capable of securing the regional security," Mousavi said.

"...Iran has repeatedly expressed its readiness to hold talks with its neighbors to resolve disputes." — Reuters