Ms Rice also revealed that the bunker beneath the White House, where she was sheltering with Vice President Dick Cheney, began to run out of air.

She said: “There were so many people in the bunker that the oxygen levels started dropping and the secret service came in and said we’ve got to get some people out of here.

“They literally went around telling people that they weren’t essential and they had to leave.”

Meanwhile, the government communication systems were failing and even Mr Bush resorted to an unsecured line to talk to Washington.