The companies have improved punctuality since the Hatfield crash and have therefore been given permission to put up ticket prices.

Some seven out of 10 London commuter companies will put up their fares by 2.5%, 1% above the 1.5% inflation figure.

The train fare changes were announced on Friday by the Strategic Rail Authority (SRA).

[It is] rewarding companies that improve their performance from absolutely disastrous to wholly unacceptable

Rufus Barnes, director of London's Transport Users committee

Since privatisation, fares on routes in and out of London have been linked to the punctuality of the train service.

The system - which is under review by the SRA - allows a company that improves on its performance the previous year to raise fares - regardless of its overall level of service.

On the other hand, companies that show no improvement on the previous year are limited on how much they can raise fares - regardless of how good their service is.

'Perverse' system

The three companies that are not putting fares up in 2003 performed comparatively well in 2001 after the October 2000 Hatfield disaster but showed little or no improvement last year.

They are: London to Southend company c2c, Chiltern Railways and South Central's inner-suburban services.

Rufus Barnes, director of London's Transport Users Committee, condemned the system which allowed the fares rise.

"It is ridiculous that the system allows the fares on the train company with the worst average punctuality (South West Trains) to increase by three times more than the company with the best average punctuality (Chiltern)."

Regulated fares

He said it had "the perverse effect of rewarding companies that improve their performance from absolutely disastrous to wholly unacceptable", whilst penalising those maintaining a generally good level.

Companies allowed to increase fares:

Connex South Eastern First Great Eastern Silverlink South West Trains Thames Trains , Thameslink West Anglia Great Northern

He welcomed the SRA review of the future fares system, saying: "One of the first things that must go is the present regime that allows the fare rises announced today."

SRA chief operating officer Nick Newton said a "common sense" system was due to be introduced from 2004.

The fares increase will only affect train users in the South East.

Regulated fares on long-distance and regional rail services will go up by only 0.5%.