US Secretary of Defence Robert Gates has dismissed suggestions that Washington had raised its rhetoric against Iran.

Mr Gates claimed that the Bush administration was instead trying to soften its tone as tensions with Tehran climb.

The comments come a day after Iranian officials said they tested missiles capable of hitting warships in the Gulf and threatened to strike US interests if Iran is attacked.

Mr Gates, appointed in December, has regularly denied claims that the US plans to attack Iran, but some defence analysts have pointed to signs such as the addition of a second US Navy carrier group in the Gulf.

Yesterday he said that the second carrier group was aimed at reassuring 'our allies'. He also said it was designed to 'send a signal that we have been in the Persian Gulf for decades and we intend to stay there'.

He again denied claims that the US planned to attack Iran,

Tensions have flared between the US and Iran in recent months, with the US suspicious of Tehran's nuclear energy programme and influence in Iraq.

US officials claim Iran is fanning violence in Iraq by giving technology and other support to Shia groups.

Mr Gates also said there was some evidence Iran was the source of technology for a particular type of sophisticated roadside bomb.