HMS montrose britain destroyer
© Reuters / Royal Navy / Ministry of Defence / Joel Rouse
HMS Montrose
The UK has confirmed reports that its warship stopped Iranian patrol boats from blocking a British tanker that was sailing through the Strait of Hormuz. Iran says these claims are absolutely "worthless."

"Three Iranian vessels attempted to impede the passage of a commercial vessel, British Heritage, through the Strait of Hormuz," the UK government said on Thursday.

According to officials, a Royal Navy frigate, HMS Montrose, was "forced to position herself between the Iranian vessels and 'British Heritage' and issue verbal warnings to the Iranian vessels, which then turned away."

The alleged incident was originally reported by CNN and Reuters, which cited unnamed US officials.

Iran denies that its boats tried to intercept the British tanker or block its path. Foreign Minister Mohammad Javad Zarif blasted the claims as "worthless" and stressed that the nation's Islamic Revolutionary Guard Corps (IRGC) had rejected the allegations made by London. The IRGC said earlier that its warships did not encounter any foreign vessels at the time when the incident is alleged to have taken place.

Zarif said that Britain had accused Iran of attempting to seize its tanker in order to "create tension" in the region.

The UK and Iran became locked in a diplomatic row last week after British Royal Marines together with Gibraltar's police boarded a Panama-flagged and Singapore-owned oil supertanker, Grace 1, near the Strait of Gibraltar. The vessel was suspected of carrying oil to Syria in violation of EU-imposed sanctions.

According to the US, the captured ship was transporting Iranian oil. Tehran acknowledged its ties to the tanker but denied that it was heading to Syria. Iranian officials blasted the seizure of the vessel as "piracy" and demanded its immediate release.