Dr Timothy Matthews, who now lives near Reading, but is originally from Coleraine, said there was little he could do without the necessary equipment.

Dr Matthews, who was travelling to an exam in London, said he was in the fifth carriage of the fast service to London's Paddington station.

"I was facing backwards and felt the impact into my back. I looked out the window and saw a scene of carnage with the other train on its side and pools of fuel on fire.

He said there were electric cables dangling, lots of smoke and fire, but people managed to remain calm.

Dr Timothy Matthews: Tried to help injured

"People in the carriage remained relatively calm in the circumstances and we managed to get out of the carriage.

"I think the over whelming thing I feel is that there are hundreds of people daily who get into public transport who are putting their lives into the hands of the people who are running it.

"You just feel tremendous vulnerability when accidents like this happen," he said.

Metropolitan Police deputy assistant commissioner Andy Trotter said that with a large number of people still unaccounted for, the final death toll could be as high as 127.

Deputy Prime Minister John Prescott, who has ordered a public inquiry, said no expense should be spared in improving train safety in the future.

Mr Prescott has decided that senior Scottish judge Lord Cullen, who looked into oil rig safety after the Piper Alpha disaster, will head the Health and Safety Executive's public inquiry into the disaster.