The Revolutionary Guard's naval commander, Gen. Ali Fadavi, told Iranian state media that the ScanEagle drone had been gathering data over the Persian Gulf. But he gave no indication of when the drone was caught.

"The US drone, which was on a reconnaissance flight and had been gathering data over the Persian Gulf in the past few days, was captured by the Guard's naval air defense unit as soon as it entered Iranian airspace," Fadavi said. "Such drones usually take off from large warships."

US navy officials have said all their drones are accounted for.

The Pentagon said last month that Iranian forces had fired at one of its Predator drones in international airspace. Iran said the drone had violated its airspace.

The incident highlighted ongoing tensions between the US and Iran over the Islamic Republic’s disputed nuclear program, which the West believes is aimed at creating atomic weapons. Iran says the program is civilian, aimed at energy production.

In December 2011, Iran said it had captured a CIA spy drone that had entered its airspace. Iran claimed to have extracted top-secret data from the stealth-technology equipped RQ-170 Sentinel drone.