WASHINGTON — The Pentagon said Monday that a ceremony marking the return of 30 US troops killed in Afghanistan would be closed to the media because their remains have yet to be identified.

President Barack Obama lifted a blanket ban on media coverage of the return of dead soldiers in 2009, leaving the choice up to families of fallen troops.

However, the Pentagon said the 30 Americans killed when a helicopter was shot down Friday could not be identified "due to the catastrophic nature of the crash."

"Because the remains are unidentified at this point, next-of-kin are not in a position to grant approval for media access to the dignified transfer," Captain Jane Campbell said in a statement.

"Therefore, in accordance with DoD (Department of Defense) policy, no media coverage of the arrival and dignified transfer is permitted."

The troops were killed after their Chinook helicopter was hit by a rocket-propelled grenade in Wardak province, southwest of Kabul, in the single deadliest incident for US forces of the nearly decade-old war.

The toll from the attack included 22 members of the elite Navy SEAL commandos, three Air Force special forces and five Army personnel. Seven Afghan troops and an interpreter were also killed.

Families of the fallen troops will be allowed to attend the arrival ceremony, which is due to take place on Tuesday at Dover Air Force Base in Delaware, officials said.

Pentagon spokesman Colonel Dave Lapan said the decision did not reflect a change in policy on media coverage of the "dignified transfer" ceremonies at Dover.

"We're only in this position because there are no identifiable remains," Lapan told reporters. There is "no change in policy at all."

Lapan could not say whether the families of the dead troops had been asked if they would approve of media coverage of the transfer ceremony, even if remains had not been identified.

The Pentagon Press Association raised concerns about the media coverage rules for the ceremony, saying in an email: "Given the high public interest in this event, we feel it is crucial to document the transfer ceremony and that the Pentagon demonstrate that it is abiding by its own guidelines."

Since the war in Afghanistan began in 2001, 149 US troops have been killed when helicopters went down in accidents or from hostile fire, according to the Pentagon.