Ministry of Defence staff who shipped ration packs out to hurricane-hit New Orleans are angry at news that most of the supplies have failed to reach the disaster area.

Two weeks ago staff at the Defence Storage and Distribution Centre in Bicester put together 500,000 ration packs to be flown out from RAF Brize Norton for the relief effort in the US.

But on arrival the ration packs were impounded in warehouses by the US Department of Agriculture because of rules on meat imports.

Leslie Sibley, a union representative for defence staff in Bicester, said: "We pulled out all the stops to get these ration packs ready and packed up and it looks like the aid that has got over is being held back by red tape.

"Everybody rushed around doing what they could to help people in their hour of need.

"Workers put their heart and soul into packing and shipping them out. It's no mean feat to shift half a million packs across the Atlantic. It's absolutely crazy."

The MoD confirmed it had flown out ration packs but said what happened to them once they reached America was out of their hands.

Foreign Office spokesman Pasquale Lamanno said about a quarter of the packs had been released from warehouses and were being distributed by the American Red Cross in Baton Rouge.

He said: "The US authorities did have concerns about the European sourcing of the ration packs."

He said negotiations over the release of the remaining packs were ongoing.

A spokesman for the US embassy in London said 180,000 ration packs had been delivered to people in the disaster area, but said they probably would not need the remaining packs as the situation had improved.

She said the packs left in the warehouse would not be destroyed but would either be sent back to the UK or kept in the US for future disaster use. The packs contain breakfast, lunch and a main dinner.