Iran's air defence force has shot down an "unknown" drone in the country's south west, the official IRNA news agency has reported.
The agency said the military hit the drone in the early morning at the port city of Mahshahr, which is in the oil-rich Khuzestan province and lies on the Persian Gulf.
The report did not say whether the drone was a military or commercially available device.
Provincial governor Gholamreza Shariati told IRNA that the drone belonged to a "foreign" country and parts of it had been recovered in a nearby lagoon.
He said the drone had violated Iran's air space.
US Central Command later wrote on Twitter that America had no drone in the area.
"All US equipment has been accounted for," it said.
The semi-official Tasnim news agency has since quoted General Alireza Sabahifard, chief of the army's air defence, as saying the drone was destroyed before reaching "sensitive" parts of the country.
He confirmed the drone was foreign but did not elaborate.
The agency also ran a short video purporting to show a missile launched in the early morning that it said hit the drone.
Tehran said that drone had "violated" its territorial air space, while the US called the missile fire "an unprovoked attack" in international air space over the narrow mouth of the Persian Gulf.
Regional tensions remain high over Tehran's collapsing nuclear deal with world powers, which the US unilaterally withdrew from over a year ago.