The top Republican and Democrat on the House Committee on Veterans’ Affairs are demanding more information from defense Secretary Chuck Hagel about lost Army field records from the wars in Afghanistan and Iraq, the subject of a ProPublica investigation last year.

In an unusually detailed letter sent Friday to Hagel, Reps. Jeff Miller, R-Fla., and Michael Michaud, D-Maine, said the Defense Department’s response to an earlier request about why records are missing — and what the military is doing about it — didn’t go far enough.

“Congress must have a clear understanding of the extent  of the lost records in order to safeguard the best interests of our service members and veterans,’’ the letter says.

The 12 questions posed to Hagel in the letter focus largely on the Army because it has the largest records deficit. Among other things, the congressmen want to know what happened to operational records for the 1st Armored Division and the 82nd Airborne Division and what is being done to reconstruct them.

In November, ProPublica and the Seattle Times reported that they were among numerous Army units that had lost or failed to keep battlefield records as required, making it harder for some veterans to obtain benefits and for historians to recount what actually happened.

“Operational records can be used to track the history of our nation’s military, plan for future operations and support innovative medical research,’’ Miller and Michaud wrote to Hagel.

In addition to chairing the veterans’ panel, Miller sits on the House Armed Services Committee, which has direct oversight responsibility for the Defense Department and service branches.

The department did not return a phone call seeking comment.