Seven people were killed in the Potters Bar crash

Jarvis was named by Railtrack's successor body Network Rail to replace track on the London North East Region which includes Potters Bar in Hertfordshire.

The track replacement work is separate to Jarvis's overall maintenance contract for London North East which runs from 2001 to 2006.

Bob Crow, general secretary of the Rail Maritime and Transport union, said the announcement was "astonishing and disgusting".

"It is an insult to all those people who died and were injured at Potters Bar," he added.

No evidence

Seven people were killed and 76 people were hurt when a West Anglia Great Northern train derailed at a set of points just outside the station on 10 May last year as it headed to King's Lynn, Norfolk.

Ten days after the crash, Jarvis said that sabotage could not be ruled out.

But an accident report last month from the Health and Safety Executive (HSE) said there was no evidence of sabotage or deliberate unauthorised interference with the points.

The HSE also said earlier inspections had not detected defects in the points at Potters Bar.

Also, the points were not adjusted properly, and there was a failure to understand their design and safety requirements.

Responding to the report, the company said last month: "Jarvis maintained the points in accordance with long-established industry procedures. "Indeed, the report gives no evidence of a failure to maintain the points within the required maintenance regime."