WASHINGTON — Defense Secretary Leon Panetta said Thursday he has ordered a review into the mistreatment of US war dead, and whether whistleblowers who balked at the mishandling of the remains were retaliated against.

Seeking to allay concerns over revelations of mismanagement at the Dover Air Force base mortuary, Panetta said Air Force Secretary Michael Donley has been asked to examine whether sufficient punishment had been meted out to the three supervisors held responsible, who were penalized for the abuses but not sacked.

"I want to make certain that we have taken all appropriate disciplinary action here. And for that reason, that's why I've asked the secretary to review that," Panetta told reporters.

He also said he wanted the Air Force to look into allegations that employees who alerted authorities to sloppy handling of remains at Dover were targeted with reprisals from managers.

A government investigative agency, the Office of Special Counsel, was looking into the allegations and once it completed its work, the Air Force secretary was expected to review the findings, Panetta said.

"This is a serious issue," he said.

Panetta said he had "directed Secretary Donley to report back to me, once the OSC (Office of Special Counsel) investigation is complete, to ensure that all appropriate action has been taken in light of that report."

The defense secretary said the Pentagon had to be held "fully accountable."

Panetta faced tough questions two days after the Air Force acknowledged "gross mismanagement" at the Dover mortuary, with body parts missing in two cases and other remains mishandled.

All American service members killed in combat abroad are transported to the Dover base, where they are identified and prepared for transfer to their families.

Since 2003, the mortuary has received the remains of more than 6,300 dead troops, mostly from the wars Iraq and Afghanistan.

The Air Force chief of staff, General Norton Schwartz, told lawmakers earlier Thursday that remains left over from the embalming process at Dover were cremated and placed in a landfill until the Air Force halted the practice in 2008.

Human remains are now buried at sea but the news has further angered some military families.

Panetta said he was first briefed on the problems at Dover when took office in July, when the Air Force was still investigating the case, and said the families involved deserved an apology.

"Listen, absolutely we should apologize. If we haven't handled those remains properly, then it is our responsibility, and we do owe those families an apology," he said.

But Panetta appeared confused about some details of the case, saying he was unaware that families were not informed of the problem until last weekend.

The Office of the Special Counsel has sharply criticized the Air Force for failing to notify families months ago and that top Air Force officials generally failed to "acknowledge culpability."

The return of troops killed on foreign battlefields carries special symbolism in a country where less than one percent of the population serves in the all-volunteer force, which has been stretched to the limit in ten years of war.

"None of us will be satisfied until we have proven to the families of our fallen heroes that we have taken every step possible to protect the honor and dignity that their loved ones richly deserve," Panetta said.