The Prime Minister Tony Blair today told Parliament that there was "absolutely no doubt" that Osama bin Laden and his al-Qa'ida organisation planned and carried out the 11 September terrorist attacks on America.
He was speaking to Parliament in a special session, recalled for the second time to consider the attacks on America and responses to it.
Mr Blair said that at least three of the 19 hijackers involved in the attacks had been positively identified as "known associates" of bin Laden and one had played a key role in the East African embassy attacks and the attack on the USS Cole.
The Prime Minister said that before the attacks, associates of bin Laden had been forewarned of a major operation and a range of people had been told to return to Afghanistan.
The Prime Minister concluded: "We act for justice. We act with world opinion behind us. And we have an absolute determination to see justice done and this evil of mass terrorism confronted and defeated."
The House was packed for the statement, which was being followed by an emergency debate on the crisis. Amid tightened security at Westminster, Mr Blair told a hushed House that there was "nothing hidden" about bin Laden's agenda.
"The attacks on September 11 bear all the hallmarks of a bin Laden operation: meticulous long term planning, a desire to inflict mass casualties, a total disregard for civilian lives, including Muslims, multiple simultaneous attacks, and the use of suicide attackers," he said
Responding for the Opposition, Tory Leader Iain Duncan Smith said: "I am convinced that Osama bin Laden, al-Qa'ida and the Taliban are guilty as charged. Any war against these people is a just war."
Mr Duncan Smith reiterated his party's support for the Government in any action, and called on the Prime Minister to consider the threat that Iraq might pose in the forthcoming conflict.