Rescuers on US stand-by

The World Trade Center was destroyed in the attack

A British rescue team is on stand-by to travel to America to help in the search for survivors after a series of terror attacks on the US.

Britain has formally offered to assist in the operation to search for survivors of the World Trade Center atrocity in New York.

Prime Minister Tony Blair made an offer to President George W Bush to assist in the aftermath of the terrorist attacks on the New York building and the Pentagon in Washington DC.

A senior member of Britain's International Rescue Corps (IRC) said his team, based at Grangemouth in Scotland, are ready to provide help for the emergency teams.

Bearing in mind the way these buildings collapsed, and their size, it is likely there will be some pockets in which people could survive

Gary O'Shea from IRC

Gary O'Shea, assistant operations director at the rescue organisation, said: "At this point, the president has not asked for outside assistance. But we and other emergency teams are on standby because the Prime Minister has made a formal offer of help."

He said that despite the devastation caused when the 1,360ft high twin towers of the World Trade Center collapsed, there was every chance that people could be alive under the rubble.

Mr O'Shea compared the disaster with major earthquake incidents such as those which have recently hit India, Turkey and Japan.

The cause might be different but the effect was the same - buildings collapsing and burying the people inside them.

"Bearing in mind the way these buildings collapsed, and their size, it is likely there will be some pockets in which people could survive," said Mr O'Shea.

"Experience and knowledge tell us that when buildings collapse voids are created and people can be trapped in these voids.

Mental grid

"You have got to focus on hope, irrespective of the nature of the disaster."

He said the usual approach would be to create a "mental grid", splitting the disaster zone up into squares which are searched one-by-one. This ensures that the same areas are not needlessly searched twice.

Heavy equipment cannot be used. Instead rescuers have to work patiently through the rubble, layer by layer, using thermal imaging equipment, sniffer dogs, and sensitive microphones to look for signs of life.

Mr O'Shea added: "You may be prioritised to go to a particular grid first; someone may have heard something, or the dogs might have indicated that somebody's there.

"You will also be looking at blue-prints of the building. You may be able to identify areas that are communal, such as a canteen, shop or boardroom."

Foreign helpers

He was not willing to hazard a guess at how long the search might take. It depended on the scale of the resources put into the operation and the difficulties encountered.

After the 1999 earthquake which devastated Armenia City in Colombia, a team of 1,700 rescue workers managed to clear the flattened city in just four days.

Mr O'Shea said even though the US probably had ample resources to carry out the operation unaided, it might still invite foreign helpers in.

"Extra expertise is always useful, and it would also allow other countries to show solidarity, to say we feel this with you," he said.

He said International Rescue had done a lot of work in the US and was in direct contact with the FBI after the Oaklahoma bombing.

The rescue body has a team of 17 experts and specialists on stand-by.