Some human remains recovered from the Sept. 11, 2001, attacks on the Pentagon and in Shanksville, Pa., were incinerated and dumped in a landfill, the Defense Department said Tuesday in the latest revelation about mishandled body parts at the Dover Air Force Base mortuary.

A new Pentagon review of the troubled mortuary disclosed several other problems — including fresh allegations of fraud and misplaced remains — over the past decade despite previous assurances by Air Force officials that they had adequately investigated operations at the base.

The revelation that “several portions of remains” recovered from the Pentagon and Shanksville ended up in a landfill was mentioned briefly on the latter pages of a report released Tuesday after an investigation led by retired Army Gen. John P. Abizaid.

The report said that the Sept. 11 remains in question “could not be tested or identified,” apparently because they were too small or charred to allow for DNA analysis. The remains were cremated and then mixed with biomedical waste at the Dover mortuary, where they were given to a contractor who incinerated them and dumped the residue in a landfill.

The report cites Army and Air Force memos from July and August 2002 directing that an unspecified number of “remains from the Attack on the Pentagon” be incinerated.

At a news conference Tuesday afternoon, Abizaid said he didn’t know many details on what happened to the remains of Sept. 11 victims.

“We did not spend a great deal of time and effort and energy looking into what you’re talking about,” he said in response to a reporter’s questions. “That was not our charge. Our charge was to look forward.”

Abizaid declined to release the memos or other documentation on the matter, saying, “I have no authority to release anything.”

Late Wednesday, the White House issued a statement saying it was “deeply concerned” about the landfill disposals and about “the unacceptable handling of remains at Dover.” The statement said President Obama had been briefed about Abizaid’s review and that he “strongly supports the Pentagon’s efforts to make needed systemic structural changes so that these types of incidents never happen again.”

The report indicates that unidentified remains from the hijacking of United Airlines Flight 93, which crashed in Shanksville, were disposed of in a similar manner. But the Pennsylvania coroner who oversaw the handling of remains from that attack said no body parts from Shanksville were ever sent to Dover or taken to a landfill.

Wallace Miller, the Somerset, Pa., county coroner, said in news reports on Tuesday that all unidentified remains from Shanksville were buried in three caskets on Sept. 12 at a memorial site for Flight 93 as part of the 10th anniversary of the hijacking.

Seeking answers

Members of Congress pressed the Pentagon to offer a more detailed account of the handling of victims’ remains.

“The heroic passengers on United Flight 93 gave the ultimate sacrifice for our nation, and their families deserve to know the fate of their remains,” Sen. Patrick J. Toomey (R-Pa.), wrote in a letter Tuesday to Defense Secretary Leon E. Panetta. “It is critically important that we get to the bottom of this matter, clear up any remaining doubts, and ensure that those responsible for any mishandling of remains be held accountable.”

In November, The Washington Post reported that the Dover mortuary for years had disposed of incinerated portions of remains of troops killed in Iraq and Afghanistan in a Virginia landfill. The practice involved unidentified or unclaimed body parts; it was not made known to troops’ family members.

The Air Force later acknowledged that it had dumped the incinerated partial remains of at least 274 service members in the landfill between 2003 and 2008, when the practice ended in favor of a new policy of burying ashes at sea.

At the time, Air Force officials said their mortuary records went back to only 2003 and that they did not know when the landfill dumping began.

On Feb. 6, however, in response to news reports about the landfill dumping, Rep. Rush D. Holt (D-N.J.) wrote a letter to Panetta asking: Could the Defense Department confirm that “no 9/11 victims’ remains were incinerated, mixed with medical waste and sent to a landfill?”

The Pentagon has not responded, according to Holt.

In an interview Tuesday, Holt accused the Pentagon of stonewalling. He said defense officials didn’t understand the importance of clearing up questions about the remains of victims of the Sept. 11 attacks and of troops killed in Iraq and Afghanistan.

“They don’t even seem to understand the gravity of the scandal,” he said. “They don’t have the degree of chagrin or embarrassment they should have.”

The top civilian and military leaders of the Air Force — Secretary Michael B. Donley and Gen. Norton A. Schwartz, the chief of staff — both said they did not know until Tuesday that some cremated partial remains of some Sept. 11 victims were ultimately taken to a landfill.

The Air Force leaders said they were focused on fixing the problems at Dover. They said they did not have any immediate plans to follow up on the disclosure about the Sept. 11 victims.

“There will be a decision, I suppose, at some point on what more time should be invested in this work,” Donley said.

George Little, a spokesman for Panetta, said the defense secretary has asked the Air Force leadership to review Abizaid’s report “and to take all steps necessary to improve operations at Dover.”

Panetta has previously told reporters that he wanted Abizaid to look into reports that troops’ body parts were cremated and sent to the landfill. But Little declined to say whether Panetta would order a further investigation into the fate of the remains of Sept. 11 victims.

“The secretary never would have supported a landfill policy,” said Little, noting that the practice ended in 2008, years before Panetta took office in 2011. “Our focus now is on ensuring that lapses that occurred in the past do not happen in the future.”

Family members of victims of the Sept. 11 attack on the World Trade Center have previously alleged that some remains of their relatives were taken to a Staten Island landfill. Family members filed a lawsuit in 2005 to force New York to search for the remains, but a federal judge ruled that the plaintiffs could not successfully prove that they had a claim to any remains.

Other incidents reported

In Abizaid’s report, an appendix lists several previously undisclosed incidents of mismanagement, mishandled body parts and other botched cases at the Dover mortuary.

In August 2009, the Air Force opened an investigation into allegations of fraud at the mortuary. The report did not disclose the nature of the alleged fraud but said the case remains open and that federal prosecutors are still deciding whether to file charges.

In January 2008, the report said, the Air Force paid a $25,000 settlement to the unidentified widow of a Marine “for mental anguish and medical costs due to loss of personal effects” that were “inadvertently destroyed” along with the Marine’s remains.

Separately, in July 2006, remains from four military personnel who died in an airplane crash were “cremated and disposed of as medical waste rather than being interred in group burial.” Abizaid’s report blamed “poor communication” among branches of the military but did not give details.

In September 2005, an Air Force investigation found that “human remains were mis-routed in a fashion constituting dereliction of duty,” according to the report, which again did not give details.