Washington says it fears Tehran may obtain classified information from stealth aircraft that Iran says it shot down.

Because the drone likely fell from a high altitude, there may be very few large pieces to examine, analysts said [IRNA]

US officials have acknowledged that the military lost control of one of its stealth drones while it was flying a mission over western Afghanistan.

Iran’s official IRNA news agency reported on Sunday that Iran’s armed forces had shot down the RQ-170, known as the Sentinel, and are now in possession of it.

US officials rejected that claim, saying there were no indications the plane was shot down. In either case, officials said this would be the first Sentinel lost by the US.

The officials said they are concerned that Iranian authorities may now have an opportunity to acquire information about the classified surveillance drone programme.

“I think we’re always concerned when there’s an aircraft, whether it’s manned or unmanned, that we lose, particularly in a place where we’re not able to get to it,” Navy Captain John Kirby, a Pentagon spokesman, told reporters on Monday.

But experts suggested that even if Iran found parts of the unmanned spy plane, which US officials admitted was used for secret CIA missions, they can probably glean little from it.

Because it likely fell from a high altitude, there may be very few large pieces to examine, analysts said.

Loren Thompson, a defence analyst with the Lexington Institute, said that stealth technologies, primarily the low-observable shape and the materials used, are fairly well known, but often hard to replicate.

“This is an aircraft that evades radar because of its shape and because of the special material used,” Thompson said. “It won’t enable the Iranians to build a stealthy unmanned aircraft.”

‘Beast of Kandahar’

The Sentinel, made by Lockheed Martin, has a swept-wing shape, much like the B-2 stealth bomber, and has been called the “Beast of Kandahar” because of its use in Afghanistan.

“They were designed to be silver bullets that could go places that other manned or unmanned aircraft would not be able to go,” said Thompson.

“It specifically is designed to be very difficult for enemies to track and target.

“This is a high-flying unmanned aircraft that malfunctioned and then fell to earth. It’s likely to be broken up into hundreds of pieces.”

John Pike, of think tank Globalsecurity, said the Iranians already have all the data on the drone’s external shape “and there is nothing particularly unique about this configuration’.’

He said the key to US success with the aircraft is the fuel-efficient engines, which give it the ability to stay aloft for days rather than hours.

“Are we going to stop flying them? No. Was it a secret we were flying them? No,” said Pike.

“Did Iran shoot it down? Probably not because Iranian air defences are not very good, and it is a good stealth vehicle.

“And did Iranian hackers hack into it and bring it down? No. It’s just too hard to do.”