Bush prepares for prime-time 9/11 address

US president George Bush has embarked on nearly 24 hours of sombre observances at the three sites where 9/11 terrorists wrought death and destruction and transformed his presidency.

He intended to offer few words during appearances at Ground Zero in New York where the World Trade Centre twin towers fell, in the Pennsylvania field where one of the hijacked planes hurtled to the ground and at the Pentagon crash site. But Americans will hear more from him during a prime-time address tonight from the White House.