Image copyright FBI Image caption Search crews appear to scour the wreckage in one of the images released by FBI

Photos taken after the attack on the Pentagon on 11 September 2001 have reappeared on the FBI's website six years after they were first released.

The 27 images show fire crews battling the blaze, as well as recovery teams and investigators searching the rubble.

American Airlines Flight 77, travelling from Virginia to LA, slammed into the building at around 09:37 local time.

US authorities said the plane struck between the first and second floors of the Pentagon, killing 184 people.

It was previously thought that the images had been newly released because of the fresh date stamp.

But FBI spokeswoman Jillian Stickels said the pictures were first posted online in 2011.

A technical glitch caused them to disappear from the site for an undetermined period of time, she added.

They were restored in recent days to public view once the FBI learned they were missing, according to the FBI spokeswoman.

Emergency response

Image copyright FBI Image caption This image was named "Pentagon Emergency Response"

Image copyright FBI Image caption Water cannons mounted on trucks brought the blaze under control

Exterior damage

Image copyright FBI Image caption This image was labelled "Pentagon Overhead"

Image copyright FBI Image caption An excavator appears to remove a shredded American flag in a photo labelled "Pentagon Exterior"

Plane debris

Image copyright FBI Image caption A photo labelled "Pentagon debris" by the FBI

Image copyright FBI Image caption This photo was tagged "Pentagon debris" by the FBI

Image copyright FBI

Investigators

Image copyright FBI Image caption Search and rescue crews examine the crash site