American intelligence officers interrogating the al-Qa'ida leader Abu Zubeida might resort to techniques considered by some to be torture, a former CIA head says.
Willliam Webster, who also led the FBI, said interrogation efforts would "go beyond name, rank and serial number" because Mr Zubeida was considered an unlawful combatant. Like the other Taliban and al-Qa'ida fighters in American custody, he would not be considered a prisoner of war.
Washington believes Mr Zubeida, described as Osama bin Laden's operations chief and the man groomed to take over leadership of al-Qa'ida, possesses a wealth of information on the terror network.
Mr Webster told the Los Angeles Times interrogators would operate on the assumption that Mr Zubeida knew about terrorist plots that might be in the planning stages. Mr Webster said: "This area is very murky. Some will want to go by the book, others will want to throw out the book."
Another counter-terrorism expert, who served in the Clinton administration, said: "It will take at least 96 hours to get him to spill everything. If they don't crack him by then, he is a very tough nut. If not, they will keep going."
Mr Zubeida is being held at an undisclosed location where he is recovering from a gun-shot wound to the groin.
A spokesman for Amnesty International said America was a signatory to the United Nations Convention on Torture, which forbid torturing prisoners under any circumstances.