U.S. military prosecutors are drawing comparisons between an Army private's alleged leak of classified documents to U.S. Civil War-era cases involving coded messages in newspapers, his defence team says, according to Belfast Telegraph.

The argument emerged during a pre-trial hearing at Fort Meade for Bradley Manning. The hearing continues later.

The issue is whether Manning's motive is relevant to a charge he aided the enemy by sending reams of classified documents to the secret-sharing website WikiLeaks.

The government contends Manning knew, or should have known, that the information would be seen by al Qaida.

Defence lawyer David Coombs said that prosecutors are citing Civil War-era cases concerning soldiers who placed coded messages in newspaper ads.

Mr Coombs said Manning's alleged offences are more akin to providing government documents to a newspaper.