Facing intense criticism of his failure to halt the anarchy and end the suffering caused by Hurricane Katrina, Mr Bush pledged: “What is not working right, we’re going to make it right.”

Later — four days after the hurricane — a huge truck convoy rolled in through the floods, bearing food, water and medicine for thousands of desperate citizens.

As corpses rotted in the toxic waters, David Vitter, a Republican Louisiana senator, said he believed that 10,000 people may have died in his state alone, most in New Orleans. A huge chemical explosion spewed acrid smoke across the city.

Mr Bush said that the Gulf Coast looked as if it had been “obliterated by the worst sort of weapon you can imagine”.

Ray Nagin, the Mayor of New Orleans, said: “They don’t have a clue what’s going on down here . . . The people of this city are holding on by a thread. Time has run out.”

Mr Bush spoke at New Orleans airport last night after touring the city by helicopter. Standing next to the Mayor, Mr Bush thanked him and said: “We are paying attention.” It was a disaster with national consequences, he said, but New Orleans would rise again.

Newt Gingrich, the former Republican Speaker of the House of Representatives, asked what was the point of all the planning for a terrorist strike. “If we can’t respond faster than this to an event we saw coming across the Gulf for days, why do we think we’re prepared for a nuclear or biological attack?”

Michael Brown, head of the Federal Emergency Management Agency, admitted that the Government had been “overwhelmed”.

Offers of aid came in from around the world, and the US Congress approved a $10.5 billion emergency aid package, which Mr Bush described as a “small downpayment” on the money that the federal Government would pour into the region.

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