LONDON -- Three Iranian ships tried to "impede the passage" of a British oil tanker as it travelled through the Strait of Hormuz, the Defense Ministry in London said on Thursday.
The incident heightens tensions in the strategic waters near the Gulf, which is a vital global oil shipping route, and comes as Iran and the US are locked in a stand-off over the 2015 nuclear accord that Washington pulled out of last year.
The British Royal Navy's HMS Montrose fended off the interception by moving in between the Iranian ships and the commercial vessel known as the British Heritage, the Defence Ministry said.
"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," a spokesman said.
Iranian Foreign Minister Mohammad Javad Zarif rejected the British claim, telling Iranian news agency Fars: "The aim of such worthless insinuations is simply to provoke tension."
The British Heritage is a Suezmax oil super-tanker owned by BP, making it one of "the largest tankers able to transit the Suez Canal in a laden condition" and capable of long voyages carrying more than 1 million barrels of oil, according to the oil giant.
"Our top priority is the safety and security of our crews and vessels," a BP spokeswoman told dpa by phone when asked about the attempted interception of the tanker.
"While we are not commenting on these events, we thank the Royal Navy for their support," she said.
President Hassan Rowhani was quoted by state media on Wednesday as vowing that there would be "repercussions" for Britain's seizure of an Iranian oil tanker off Gibraltar last week.
Shipping monitoring service Lloyd's List reported on Tuesday that the British Heritage had "diverted and failed to load its 140,000 tonne cargo of crude at Basrah, Iraq, as planned on July 4 -- the day Grace 1 was intercepted off Gibraltar."