WASHINGTON - US Defence Secretary Chuck Hagel has ordered the Pentagon to reorganize its much-criticised effort to account for US troops missing from foreign wars, creating a single agency to improve accountability and speed recovery and identification of remains.

Hagel's announcement came as the US Congress is putting pressure on the Defence Department to boost its accounting for some 83,000 missing US troops - about 73,000 from World War Two and 10,000 from other conflicts.

The Pentagon spends about $100 million per year on the effort and identifies the remains of about 70 people annually, but it is under a congressional mandate to boost its capacity to 200 annually by the 2015 fiscal year beginning in October.

"There's not a more poignant, emotional, important issue in our society today ... than you take care of the people who gave their lives to this country, and you take care of their families," Hagel told a Pentagon news conference.

"We will continue to do everything we can to account for and bring as many of our missing and fallen service personnel as possible home here to the United States," he said.

An investigation by the Government Accountability Office last year said the effort to recover and identify missing military personnel was "undermined by longstanding leadership weaknesses and a fragmented organizational structure."

Hagel ordered the Pentagon to consolidate two different offices involved in the effort to account for missing personnel, as well as parts of an Air Force laboratory, into a single agency to be led by a civilian appointee.

"By consolidating functions, we will resolve issues of duplication and inefficiency and build a stronger, more transparent and more responsive organization," Hagel said.

He said the new organization would be responsible for all communications with family members of troops missing from past conflicts, giving them a single point of contact for information.

Hagel said a single military medical examiner would be named as the authority responsible for identifications, and that the agency would create a centralized database and case management system to track information about missing troops.

The Pentagon chief said he would work with Congress to consolidate all funding for the accounting mission under the new agency.

Mike Lumpkin, the acting undersecretary of Defence for policy, said later the Pentagon spends about $100 million annually to locate and identify the remains of missing American military personnel. He said the funding commitment was expected to remain the same for the new agency.

Lumpkin, who crafted the recommendations for the overhaul, told reporters the current effort was hampered by "outdated, institutionalized thinking." He said the new agency needed to "break away from the traditional way of doing business."

He said that meant not only working the issues in-house at the Defence Department, but also partnering with outside groups that work on related issues, such as universities or people doing research on genealogy or searching for lost planes.

Of the approximately 83,000 missing US military personnel, some 43,000 are considered unrecoverable without additional information or the discovery of new technologies.