Iran rejects tanker attack allegations, says US claims 'unsubstantiated'

Iran's defence minister "categorically rejected" Wednesday accusations that Tehran was behind two tanker attacks in the Gulf of Oman, describing evidence presented by Washington as "unsubstantiated", official news agency IRNA reported.

Washington has blamed Iran for last week's attacks, releasing images and a grainy video it alleges shows Iranians on a patrol boat removing an unexploded limpet mine attached to one of the tankers.

"Accusations levelled against Iran's armed forces and the published film with regards to the incident (that) happened to the vessels ... are unsubstantiated and we categorically reject these accusations," IRNA quoted Defence Minister Brigadier-General Amir Hatami as saying.

"The armed forces and the port organisation were among the first to approach the tankers after the incident for relief operations and they rescued 23 people in the first tanker," he added.

Hatami did not explicitly specify which of the two ships he was referring to, but Iran's English-language Press TV at the time broadcast footage of 23 sailors rescued from the Front Altair, a tanker owned by a Norwegian listed company.

Hatami added that the Iranian forces then headed to the second tanker, but the crew announced another vessel had already rescued them. "This means Americans had arrived sooner to the scene where they claim the video was recorded at," Hatami said, with apparent reference to the Japanese-owned Kokuka Courageous.

According to a US navy spokesman, the 21 sailors from the Kokuka Courageous abandoned ship after "discovering a probable unexploded limpet mine on their hull following an initial explosion", before they were picked up by a Dutch tugboat.

The sailors were transferred to the USS Bainbridge and US Central Command later released a video it said showed an Iranian patrol boat removing the mine from the hull of the Kokuka Courageous, but it has not provided an explanation as to why the patrol boat allegedly did so while the US military was observing.

Iran's Foreign Ministry had already dismissed the US allegations that it was behind the attacks as "baseless" and slammed Saudi Arabia and Britain -- where Foreign Secretary Jeremy Hunt has alleged Iran was "almost certainly" responsible for the attacks -- for following the US line.

Tensions between Tehran and Washington have grown since the US unilaterally quit the multilateral 2015 nuclear deal last year and reimposed sanctions on Iran. The US has bolstered its military presence in the Middle East and blacklisted Iran's Revolutionary Guards as a terrorist organisation.