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 gave no indication of when the drone was caught.

"We have no evidence that the Iranian claims… are true," Carney told journalists.

US military also rejected the information.

"The US Navy has fully accounted for all unmanned air vehicles (UAV) operating in the Middle East region. Our operations in the Gulf are confined to internationally recognised water and air space," Commander Jason Salata, from the US Navy's 5th Fleet, was quoted as saying by Sky News.

"We have no record that we have lost any ScanEagles recently," he added.

This is the third reported incident involving Iranian forces and American unmanned aircraft in the past 12 months.

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.

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.

The incidents highlight ongoing tensions between the US and Iran over the Islamic Republic’s disputed nuclear program.