A US Army private facing court-martial on suspicion of leaking secret documents to the WikiLeaks website testified on Thursday he was confined to a "cage" in the early days after his arrest in 2010 and thought he would die there.

Bradley Manning, in his first public comments since his arrest in Iraq, said his isolation led to a rapid decline in his awareness of his surroundings.

He said that he was initially given little or no information about the charges against him.