Top-secret “stealth helicopter” used in raid that killed Osama bin Laden (VIDEO)

The helicopters used in the Navy SEAL raid to take out Osama bin Laden on May 1 were equipped with top-secret stealth modifiers that allowed the choppers to silently sneak up on the luxury Pakistan compound where bin Laden had been living, aviation experts say.

The helicopters, which reportedly have a different look than other military helicopters — sharper angles and flat surfaces more common to stealth jets — and are equipped with noise-reducing technology, have reportedly never been seen before.

In the course of the operation, according to ABC News, one of the two Black Hawk helicopters that carried the SEALs into bin Laden's compound grazed a compound wall and was forced to make a hard landing. SEALs were forced to abandon the chopper but attempted to destroy it with explosives before departing.

Photos of the wreckage left behind — the tail section of the craft — were shown in photographs of the raid that killed bin Laden, published by ABC. 

The photos have prompted speculation that the chopper is a secret, highly-modified version of the military's iconic Black Hawk. 

Avation Week reported that the chopper's tail appears to be highly modified compared to a standard H-60 Black Hawk. The report noted that stealth features on a helicopter usually aim to dampen rotor noise and reduce infrared signals.

The military has been working to improve the Black Hawk helicopter since at least 2004, according to ABC. The machine has been in use since 1979. 

A senior Pentagon official said the Defense Department would “absolutely not” comment on the helicopters shown in the photos.