Pte First Class Bradley Manning has apologised for hurting the US by leaking a trove of classified US government documents to Wikileaks, BBC News reported.

At a sentencing hearing in Fort Meade, Maryland, Pte Manning, 25, said he had mistakenly believed he could "change the world for the better".

And he said that in retrospect, he should have worked "inside the system".

Pte Manning, 25, faces up to 90 years in prison following his conviction in July on 20 espionage and other charges.