The Iranian Air Force's F4 Phantom jets have conducted several airstrikes against the Islamic State (IS) positions in eastern Iraq during recent days, a US military official has confirmed.
Pentagon spokesman rear admiral John Kirby said: "We have indications that they did indeed fly air strikes with F-4 Phantoms in the past several days.
"We are flying missions over Iraq, we co-ordinate with the Iraqi Government as we conduct those.
"It's up to the Iraqi Government to deconflict that airspace."
Last week, Al-Jazeera aired footage that showed an F-4 fighter, similar to those operated by the Iranian Air Force, conducted a bombing run against ground IS targets over the eastern Iraqi province of Diyala.
However, Kirby said the US is not co-ordinating with Iran to launch air strikes in the Iraqi territory.
He added: "Nothing has changed about our policy of not co-ordinating military activity with the Iranians."
Iranian Armed Forces deputy chief of staff General Massoud Jazayer also denied reports that Iranian fighters have bombed IS positions in collaboration with the US.
Jazayeri was quoted by Fars News Agency as saying: "The Islamic Republic of Iran blames the United States as the root cause of unrest and problems, as well as the terrorist actions of ISIL in Iraq."
Meanwhile, a US official told the Huffington Post that the US was aware of Iranian bombing activity in Iraq, and would not respond unless Iran presents a threat to US ground forces.
According to media reports, Iran has already supplied weapons and equipment, including Su-25 attack jets, to the Shi'ite-led Iraqi Government to help in the fight against IS, which currently controls a large territory in Iraq and Syria.
In addition, Shi'ite militias, trained and funded by Iran, have been deployed to Iraq to support Kurdish Peshmerga fighters battling the militants, as reported by BBC News.
Since August, US and coalition fighters, bombers and surveillance aircraft have been flying daily missions over Iraq, and the fight was extended into Syria the following month.
Image: The US has confirmed media reports that Iranian Air Force F-4 fighter launched airstrikes against Islamic State targets in Iraq. Photo: courtesy of Shahram Sharifi.