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 retrial of the man charged with helping the September 11 terror bombers may collapse, it emerged in Hamburg today.

The Hamburg al-Qaida cell that included three of the September 11 hijackers planned an attack on the World Trade Centre as early as April or May 2000, a German prosecutor said today.