The Revolutionary Guards in Iran claim to have shot down two "Western spy drones" in the Gulf.
The Fars news agency quoted the Guards' air force commander Amir Ali Hajizadeh as saying "many" other drones have been shot down over an unspecified period of time.
No evidence was produced to support the report, but the Guards said this was the first time that news of such incidents had been reported.
Drones are mainly being used in Iraq and Afghanistan, but the commander said "some violations against our soil" had also occurred.
The BBC reports there is no independent corroboration of the claim.
The Revolutionary Guards were set up following the Islamic revolution in 1979.
The Fifth Fleet of the US navy is based in Bahrain, on the other side of the Gulf from Iran.
