Iran threatened to shoot down US aircraft in Gulf: Report

The Iranian military threatened to shoot down two US navy aircraft flying over the Strait of Hormuz, a US defence official told the AFP news agency on Tuesday.

The claim is the latest in a string of confrontations between the Iranian and US military in the Gulf.

Two "maritime patrol aircraft" were flying separate missions in a similar area in international air space earlier this month when they received three radio calls from Iranian air defence.

"They were threatening to shoot at us, to shoot us down, or fire missiles at us," the US defence official said.

The official, who was not named by the AFP, said the US government would make a formal announcement about the confrontation. 

According to Fox News, which first reported the encounter, the US planes ignored the warning and continued on their mission.

One unnamed defence official told the news network that the US military had wanted to test the Iranians' reactions.

The defence official spoken to by AFP said the incident was "unprofessional" but was not deemed unsafe because the US planes were outside the bounds of known Iranian anti-aircraft missile ranges.

The Pentagon has in recent weeks denounced a series of "unsafe and unprofessional" maritime encounters in the Gulf, including one that prompted an American ship to fire warning shots at an Iranian vessel that got too close.

Navy officials say ships from the US and Iranian navies interacted more than 300 times in 2015 and more than 250 times the first half of this year, with 10 percent of those encounters deemed "unsafe and unprofessional".

In January, the Iranian navy briefly captured the crews of two US patrol boats that had, through a series of blunders, strayed into Iranian territorial waters.

The 10 American sailors were released within 24 hours.