RAF pilots have tried to blast UFOs out of the sky under a top-secret British government directive, it was claimed Sunday night.

Nick Pope -- who worked on the Ministry of Defense's UFO desk for three years -- revealed the rules of engagement for the first time.

He claimed RAF pilots had fired at UFOs on several occasions -- but failed to bring them down.

He added: "We know of cases where the order has been given to shoot down -- with little effect to the UFO."

Pope said the rules of engagement were drawn up after dozens of close encounters with suspect craft in British airspace.

RAF attacks on UFOs were "not automatic but happen when something in our airspace is deemed to be a threat."

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