The lawyer defending an accused accomplice of the September 11 suicide pilots at his Hamburg retrial has been critically injured in a motorbike accident, throwing into question how the case will proceed.

A senior planner of the September 11 2001 attacks said the Hamburg al-Qaida cell was smaller than investigators believed, consisting only of himself and three of the suicide pilots, a German court was told in the first public release of statements by suspects in US custody.

The re-trial of the only September 11 terror suspect ever convicted opened today with the United States under pressure to allow testimony by alleged key al-Qaida operatives in its custody.

LAWYERS for the only man convicted over the September 11 attacks in the United States said yesterday they will call for the case against him to be thrown out when he returns to trial this month.