WASHINGTON — The mortuary at Dover Air Force Base in Delaware disposed of body parts of some victims of the Sept. 11, 2001, attacks by burning them and dumping the ashes in a landfill, an independent panel said in a report to the Pentagon released on Tuesday.

The startling new disclosure was the latest to tarnish the reputation of Dover, hallowed ground for the military and the entry point for the nation’s war dead, and is likely to create further anguish among families of the Sept. 11 victims.

Mortuary officials had already been under fire for what the Air Force termed “gross mismanagement” for losing the body parts of two service members in 2009, repeated failures of command, doing little to change sloppy practices and sawing off the protruding arm bone of a dead Marine without informing his family.

The method of disposal of the Sept. 11 body parts was limited to what the report said were “several portions of remains” that could not be identified from the attack on the Pentagon and the crash site in Shanksville, Pa. The report said the remains were cremated and placed in containers provided to a biomedical waste disposal contractor, which then incinerated them and put them in the landfill.