Bradley Manning, the US soldier convicted for giving classified documents to the WikiLeaks website, exhibited behaviour that could have served as a warning he was unsuitable to serve abroad as an intelligence analyst, his lawyer has said.

As the defence began its case in the sentencing phase of Manning's court-martial at Fort Meade, Maryland, on Monday, lawyers discussed a psychological assessment report that describes him as having "regressed stages of development" and "narcissistic personality traits".

Manning's lawyer, David Coombs, said the report was important to explain the motivation for the unauthorised release of more than 700,000 diplomatic and military documents and videos, the biggest leak of classified information in US history.

"It's mostly to explain to the court what was going on," Coombs said. He also said Manning would make a statement during sentencing.

Listening Post - Bradley Manning: Truth on trial?

Outburst during counselling

The defence tried to show on Monday that army commanders failed to notice personality traits that might have made Manning unfit to serve as an intelligence analyst in Iraq, where he released secret files to anti-secrecy website WikiLeaks in 2010.

Prosecutors objected, saying the defence should not be allowed to use the report because they were not given prior notice. Coombs questioned Manning's brigade commander, Colonel David Miller, about whether mid-level officers failed to respond properly to behaviour by Manning showing he should not be placed in an intelligence analyst position.

The court heard how Manning had been referred for counselling in December 2009 and during a session, he flipped a table and in another outburst, tried to grab a gun but was restrained by another soldier.

Manning, 25, was convicted on July 30 of 20 counts, including espionage and theft.

He was found not guilty of the most serious count of aiding the enemy, which carried a sentence of life without parole.

Manning was referred to counselling in December 2009, Miller testified. Miller said he was not told about Manning's behaviour until after the leaks were published.

Source: Agencies