Thousands of agents deployed in WTC investigation

FBI director Robert Mueller has said that 4,000 special agents, 3,000 support personnel and 300 lab workers have been deployed at various sites around the US as part of the investigation into the World Trade Centre bombings.

"Our first objective was to identify the hijackers and their associates, to remove their associates and thereby remove the threat to our airspace," he said.

Mr Mueller, who confirmed that no arrests had yet been made, said some of the hijackers had already been identified.

"We have already identified a number of individuals who may have had something to do with the hijackings and we are pursuing those leads aggressively," he said.