US authorities have filed the first criminal charges in their investigation into the terrorist attacks after finding three men with false immigration papers and airport diagrams.
The arrests occurred when FBI agents raided a house in Detroit yesterday looking for one of the nearly 200 witnesses being sought in the investigation.
Instead, they found the three men and a cache of documents. The three were charged with having false immigration papers.
The investigation has detained 75 people for questioning and had at least four people under arrest as material witnesses, law enforcement officials said. A material witness is someone considered crucial to the investigation whom authorities may detain without charging with any crime.
The US government also announced a new policy that gives immigration authorities two days, or longer in emergencies, to decide whether to charge an alien with status violations, up from one day. Many of those questioned over the attacks were being detained on immigration violations.
US Attorney General Mr John Ashcroft - the top US law enforcement official - promised to use "every legal means at our disposal to prevent further terrorist activity by taking people into custody who have violated the law and who may pose a threat to America."
Mr Ashcroft said publicly for the first time that authorities were investigating whether more flights than the four that crashed last Tuesday had been targeted for hijackings.
The restructuring of the investigation included the creation of anti-terrorism task forces by every federal prosecutor's office in the country.
"These task forces will be a part of a national network that will coordinate the dissemination of information and the development of a strategy to disrupt, dismantle and punish terrorist organisations throughout the country," he said.
The effort was being aided by a grand jury investigative panel in the New York suburb of White Plains that subpoenas witnesses and determines whether to file indictments against suspects. Officials said other grand juries would probably be used around the country to issue subpoenas and gather evidence.
PA