US Congress begins closed hearings into possible intelligence failures in the run-up to the attacks of 11 September. A series of recent revelations suggest that clues were missed prior to the attacks.

FBI Director Robet Mueller says investigators believe that the idea for the 11 September attacks originated with al-Qaeda leaders in Afghanistan, was planned in Germany and financed with funds from the United Arab Emirates and Afghanistan. Mr Mueller also said that Khalid Shaikh Mohammed, a 37-year-old Kuwaiti believed to be in hiding in Afghanistan, played the key role in planning the attacks. Khalid Shaikh Mohammed is alleged to be a senior plotter on the basis of information given to US authorities by Abu Zubaydah, the most senior al-Qaeda official in US custody.

An official at the German Justice Ministry, Thomas Weber, says that Berlin is reluctant to hand over evidence that might assist in the prosecution of Zacarias Moussaoui because he could face the death penalty.

Moroccan authorities announce the arrest of three alleged al-Qaeda members in connection with a plot to attack American and British naval ships in the Straits of Gibraltar.

The Saudi Arabian authorities announce that they have arrested 13 alleged al-Qaeda members accused of plotting an attack in the kingdom. Press reports say that the suspects were planning to launch a ground to air missile at a US plane taking off from an air base in Saudi Arabia.

The Moroccan authorities hand over an alleged leading member of al-Qaeda to Syria. Mohammed Haydar Zammar, a German citizen of Syrian origin was arrested in Morocco. He is alleged to have liaised between Mohammed Atta and al-Qaeda leaders in Afghanistan.

Moroccan security officials also announce the arrest of Abu Zubair, a Saudi national alleged to be a leading al-Qaeda recruiter.

A bill is passed in House of Representatives that will make it easier for federal agencies to share information about terrorism with local and state authorities. For the first time, the legislation makes co-ordination between the FBI and CIA a legal requirement.

A Jordanian national suspected of being a former roommate of some of the 11 September hijackers is arrested in the US. Ramzi al-Shannaq is detained on visa irregularities by the FBI. It is alleged that for two months last year, the Jordanian shared an apartment in Virginia with Nawaf al-Hazmi and Hani Hanjour - two men alleged to have been on the plane that crashed into the Pentagon.