Iran has dismissed as "fabricated" reports of the seizure of a British oil tanker in the Gulf, Iran's IRIB news agency quoted unnamed sources as saying.

On Twitter, some reports said a British-flagged supertanker called 'Pacific Voyager' had come to a halt in the Gulf.

An Iranian Revolutionary Guards commander threatened on Friday to seize a British ship in retaliation for the capture of an Iranian supertanker by Royal Marines in Gibraltar on Thursday for trying to take oil to Syria in violation of EU sanctions.