Passengers and staff involved in the Paddington rail crash are to be offered counselling from the two train companies involved.

Their families are also to get confidential help in coming to terms with the disaster.

Doctors, nurses and ambulance staff who treated the injured and attended the scene are also likely to be offered help.

The fear is that those who are affected by or witnessed the event will suffer severe psychological distress, in particular post-traumatic stress disorder (PTSD).

Lasting effects

PTSD can lead to painful memories of the event revisiting the victims at any time, forcing them to relive the experience.

The effects can last for years - some victims of the Southall rail crash are still traumatised by the incident.

The trauma can lead to feelings of isolation and a sense of losing control - patients sometimes turn to alcohol or other drugs as they attempt to get rid of the memories.

Jonathan Street said traumatised patients would get counselling

It is also known as shell shock because it first came to prominence when soldiers in the First World War were afflicted by memories of the horrors they saw in the trenches.

However, counselling is not the first priority for those victims still in hospital.

Jonathan Street, of St Mary's Hospital in London, told the BBC: "Our first priority is to get them through the first phase of treatment - their medical and surgical treatments.

"Then if they need psychological counselling, then they will get that."

Bystanders counselled

Meanwhile, the train companies involved are making their own offers of help.

Great Western is writing to all those who were taken to hospital with an offer of individual or group counselling to those who want it. Staff have also been offered the help.

Thames Trains announced a similar measure.

The Sainsbury's store near the site of the crash has also called in counsellors to help employees who assisted victims at the scene.

Dealing with issues

Icas, the independent firm of counsellors that provided help after the Southall rail crash, is involved with the Paddington accident.

A spokesman for Great Western said: "The service is available today, tomorrow or in six months' time.

"Everyone deals with these situations in different ways. The service is being offered and it is up to individuals or groups to follow it through if they wish."

Vince Balzan, manager of the Sainsbury's Ladbroke Grove store, said some of staff had said they were so shocked by the crash that they could not come into work the following day.

"We have paid for counsellors to help staff who have problems. I am extremely proud of all their work," he said.