The White House vetoed a raid to kill or capture most of al Qaeda's high command hours before it was due to be launched in 2005, according to US military sources.

US Navy Seal commandos were waiting in full combat kit in the aircraft which were to drop them over the lawless tribal territories inside Pakistan when the order came to stand down.

The target was a meeting of senior terror network commanders and strategists - including Dr Ayman al-Zawhahiri, Osama bin Laden's deputy - in a remote compound in north Waziristan.

A Pentagon source said yesterday: "The White House got cold feet at the 11th hour. There were fears that the operation might either end in a fiasco like the attempt to rescue US hostages in Iran in 1980 or that it would destabilise Pakistan's President Pervez Musharraf's rule.

"One of the main problems was that, for once, we had solid intelligence on the location of key al Qaeda players.

"At that point, everyone and his brother wanted in on the act. It went from a surgical strike by a small commando team from the Seals to a major operation involving hundreds of troops from the Army's Rangers and the CIA's special operations paramilitaries.

"It would have looked a lot like an invasion of Pakistan. There were just too many fingers in the pie."

Donald Rumsfeld, then US defence secretary, cancelled the mission as the paratroop aircraft sat with engines running at an Afghan airbase. The US State department said such an operation might undermine President Musharraf, already facing severe opposition from groups hostile to his co-operation with the West.

The CIA, whose agents had obtained details of the terrorist summit, appealed to the White House to allow the mission to proceed, but this approach was finally blocked by Rumsfeld. Despite five years of the most intensive surveillance in history, US agencies are no closer to pinpointing the location of either bin Laden or al Zawahiri.

They are believed to be hiding separately in the mountainous tribal lands along the 1500-mile border between Pakistan and Afghanistan.

Al Zawahiri, an Egyptian doctor, is al Qaeda's operational director and the organisation's main strategist.