TEHRAN, Iran -- Iran claimed Tuesday it had captured a U.S. drone after it entered Iranian airspace over the Persian Gulf- even showing an image of a purportedly downed craft on state TV - but the U.S. Navy said all its unmanned aircraft in the region were "fully accounted for."

The conflicting accounts still leave the possibility that the drone claimed by Iran, a Boeing-designed ScanEagle, could have been plucked from the sea in the past and unveiled for maximum effect following escalating tensions over U.S. surveillance missions in the Gulf.

Other countries in the region - such as the United Arab Emirates - also have ScanEagle drones in their fleets.

Cmdr. Jason Salata, a spokesman for the U.S. Navy's 5th Fleet in Bahrain, said ScanEagles operated by the Navy "have been lost into the water" over the years, but there is no "record of that occurring most recently."

The Iranian announcement did not give details on the time or location of the claimed drone capture.

It's certain, however, to be portrayed by Tehran as another bold challenge to U.S. reconnaissance efforts in the region. Last month, the Pentagon said a drone came under Iranian fire in the Gulf but was not harmed. A year ago, Iran managed to bring down an unmanned CIA spy drone possibly coming from Afghanistan.

Iran also has recently alleged repeated airspace violations by U.S. drones, which Washington denies.

"The U.S. Navy has fully accounted for all unmanned air vehicles operating in the Middle East region," said Salata. "Our operations in the Gulf are confined to internationally recognized waters and airspace."

Iran claimed it captured the drone after it entered Iranian airspace. A report on state TV quoted the navy chief of Iran's powerful Revolutionary Guard, Gen. Ali Fadavi, as saying the Iranian forces caught the "intruding" drone, which had apparently taken off from a U.S. aircraft carrier.

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

Al-Alam, the Iranian state TV's Arabic-language channel, showed two Guard commanders examining what appeared to be an intact ScanEagle drone. It was not immediately clear if that was the same drone Iran claimed to have captured.

In the footage, the two men then point to a huge map of the Persian Gulf in the background, showing the drone's alleged path of entry into Iranian airspace.

"We shall trample on the U.S," was printed over the map in Farsi and English next to the Guard's emblem.

If true, the seizure of the drone would be the third reported incident involving Iran and U.S. drones in the past two years.

Last month, Iran claimed that a U.S. drone had violated its airspace. Pentagon said the unmanned aircraft came under fire - at least twice but was not hit - and that the Predator was over international waters.

The Nov. 1 shooting in the Gulf was unprecedented, and further escalated tensions between the United States and Iran, which is under international sanctions over its suspect nuclear program. Tehran denies it's pursuing a nuclear weapon and insists its program is for peaceful purposes only.

In late 2011, Iran claimed it brought down a CIA spy drone after it entered Iranian airspace from its eastern borders with Afghanistan and Pakistan. The RQ-170 Sentinel drone, which is equipped with stealth technology, was captured almost intact. Tehran later said it recovered data from the top-secret drone.

In the case of the Sentinel, after initially saying only that a drone had been lost near the Afghan-Iran border, American officials eventually confirmed it had been monitoring Iran's military and nuclear facilities. Washington asked for it back but Iran refused, and instead released photos of Iranian officials studying the aircraft.

The U.S and its allies believe Iran is pursuing a nuclear weapon. Iran denies the charge, saying its nuclear activities are for peaceful purposes only, such as power generation and cancer treatment.

Iran meanwhile, has claimed advanced in drone technology.

In November, Iranian media reported that the country had produced a domestically-made drone capable of hovering. Earlier, Iran said it obtained images of sensitive Israeli bases taken by a drone that was launched by Lebanon's Hezbollah and downed by Israel.

Iran also claimed other drones made dozens of apparently undetected flights into Israeli airspace from Lebanon in recent years. Israel has rejected the Iranian assertions.

Associated Press