The grainy clip, lasting five minutes and 20 seconds without sound or narration, showed a man speaking into a handheld radio, with three US ships in the distance.

The footage appeared to be shot from a small vessel operating at least 100 metres away from the American warships.

Contrary to the American's version of events, however, the video did not show any Iranian boats approaching or provoking the US fleet.

Yesterday, the Pentagon released its own video of the incident, which showed Iranian boats swarming around three US warships in the Strait of Hormuz.

Audio revealed how one man, believed to be commanding the Iranian boats, had threatened the warships, saying: "I am coming to you. ... You will explode after ... minutes."

Despite this, Iranian state-run channel Press TV later said officials from the Revolutionary Guard had claimed the US footage had been doctored.

"The footage released by the US Navy was compiled using file pictures and the audio has been fabricated," a source said.

Press TV did not give the name of the Revolutionary Guard spokesman, or offer any evidence that the footage had been altered.

Since the incident, which occurred in a crucial international oil shipping route, the US has condemned the Iranian standoff as a "provocative act".

President Bush's national security adviser, Stephen Hadley, said it was "not a smart thing to do, and they [the Iranians] are going to have to take responsibility for the consequences, if they do it again".

In the US version of the incident, a four-minute, 20-second video showed the Iranian boats appearing to ignore repeated warnings from US warships. One crew member on the bridge of the destroyer USS Hopper is heard addressing the Iranian's over the radio saying: "This is coalition warship. I am engaged in transit passage in accordance with international law. Intend no harm."

Iran's version of the encounter, however, included no such audio. It also did not appear to show the entire standoff, which Washington officials have said lasted about 20 minutes.

Yesterday, Iran's defence minister, Mostafa Mohammad Najjar, called western news reports, suggesting Iranian boats had threatened to blow up the US warships as "mischief". "[Iranian] Navy units ... asked them to identify themselves. They responded accordingly and continued their path," the official IRNA news agency quoted Najjar as saying.

He also reiterated previous comments made by Iran's foreign ministry, downplaying the incident by calling it something that occurred regularly.

The incident, which ended without any shots fired, has heightened US Iranian tensions as President George W Bush continues his Middle East tour today.