The incident, between two stations in Birmingham, caused a week of delays for thousands of passengers on the Dorridge and Stratford lines.

On Tuesday Chiltern Railways said its service between London Marylebone and Birmingham had returned.

Central Trains said a full service had resumed on its Snow Hill lines.

Task force

A spokesman for Chiltern Railways said Network Rail engineers had been working around the clock to get the service up and running.

In a statement Chiltern Railways said: "We'd like to apologise to all of you who've faced disruption as a result of this arson attack, and thank you for your patience throughout the past week."

Last week Railtrack offered a �50,000 reward for information leading to the conviction of those responsible for the arson attack.

It is thought equipment cabinets, between Small Heath and Tyseley stations, in Birmingham were set on fire.

It is being linked to a series of similar incidents in the West Midlands and Warwickshire area and British Transport Police have set up a new task force to investigate.