The document says the failure to kill or capture the al-Qaeda leader in the mountains of Tora Bora in Afghanistan at his most vulnerable in December 2001 has had lasting consequences.

Bin Laden’s escape laid the foundation for the reinvigorated Afghan insurgency and inflamed the internal strife now endangering Pakistan, it says.

The Senate Foreign Relations Committee’s Democratic majority prepared the report at the request of the chairman, Sen John Kerry, as President Barack Obama prepares to boost U.S. troops in Afghanistan.

Mr Kerry, the 2004 Democratic presidential candidate, has long argued the Bush administration missed a chance to get the al-Qaeda leader and top deputies when they were holed up in the forbidding mountainous area of eastern Afghanistan only three months after the Sept. 11, 2001, terrorist attacks.

The report puts part of the blame for the state of the war today on military leaders under former President George W Bush, specifically Donald Rumsfeld as defence secretary and his top military commander, Tommy Franks.

"Removing the al-Qaeda leader from the battlefield eight years ago would not have eliminated the worldwide extremist threat," the report said. "But the decisions that opened the door for his escape to Pakistan allowed bin Laden to emerge as a potent symbolic figure who continues to attract a steady flow of money and inspire fanatics worldwide."