Image copyright AFP Image caption The plea offer is the first sign Manning will admit leaking thousands of secret documents

The alleged source of the Wikileaks revelations has offered to plead guilty to lesser offences than those with which he is charged, says his lawyer.

US Army Private Bradley Manning faces a life sentence if found guilty at his Maryland court martial of aiding the enemy - one of 22 charges he faces.

His lawyer David Coombs made the offer at a pretrial hearing on Wednesday.

The offer is the first sign he will admit leaking secret Afghanistan and Iraq war reports and diplomatic cables.

But it suggests he will not plead guilty to aiding enemies of the US (identified by prosecutors as al-Qaeda in the Arabian Peninsula), violating federal espionage and computer laws - charges for which he could face life in prison if found guilty.

The intelligence analyst, who is now 24, is alleged to have been the source of the series of high-profile security breaches that saw Wikileaks rise to global fame.

They released a video showing US troops firing on Iraqis from a helicopter, caches of documents from both the Iraq and Afghan wars, and a huge haul of classified state department cables.

Trial by judge alone

Pte Manning was "attempting to accept responsibility for offences that are encapsulated within, or are a subset of, the charged offences," wrote Mr Coombs in a blog post.

The court would have to decide whether it was "permissible" for his client to take such action, he added.

Even if the court allows Pte Manning to take the action - known as "pleading guilty by exceptions and substitutions" - the government could still press ahead with the original charges, acknowledged Mr Coombs.

"Pleading by exceptions and substitutions, in other words, does not change the offences with which PFC Manning has been charged and for which he is scheduled to stand trial," he said.

The judge, Col Denise Lind, is set to consider the plea at a hearing on 10 December unless the offer is withdrawn.

Pte Manning has also elected to be tried by military judge alone, rather than a judge and panel of military officers, added his lawyer.

The defendant, who has been in custody since his arrest in Iraq in May 2010, is currently being held at Fort Leavenworth, Kansas.

His six-week trial is due to start on 4 February.