An Army private charged in the biggest leak of secrets in U.S. history is pressing prosecutors for evidence he hopes will bolster his defense.

Pfc. Bradley Manning is set to appear at a pretrial hearing Monday afternoon at Fort Meade in Maryland.

Manning is seeking reports from various government agencies assessing the damage done by his alleged leak of classified diplomatic cables and war logs to the secret-sharing website WikiLeaks.

His lawyers claim prosecutors are balking at giving them copies of the damage assessments.

Manning also is asking the military judge to postpone his September trial date to give both sides more time to obtain and study the documents.

The judge indicated during a hearing earlier this month that the trial probably will be postponed to November or January.