A rail passengers' group has attacked two train companies for forcing travellers to sit in the dark for two hours after a mechanical failure.

Some of the passengers became so fed-up they forced open doors and started walking along the track to nearby platforms.

In an investigation by the Rail Passengers' Committee, released today, the watchdog wants Thameslink and Connex to apologise publicly to commuters who were caught in the incident on October 20.

A mechanical failure caused a Thameslink train to stall and block several lines outside Brighton station.

Eight trains, including Connex stock, were caught behind it and power was turned off to allow repairs to be made.

After half an hour passengers on trains were plunged into darkness when the emergency lights went off.

Some commuters forced open doors and scrambled along railway banks and tracks to nearby roads and platforms, leaving Railtrack with no option but to switch off power to ensure no one was electrocuted.

Wendy Toms, chairman of the committee's southern England branch, said: "We have yet to see any public apology from the two companies to passengers, some of whom were trapped in this train while other frustrated passengers took matters into their own hands, left their trains and decided to walk along the track.

"Instead, both Connex and Thameslink responded to our investigations with statements blaming passengers.

"It is, of course, always dangerous for passengers to walk along the track, which is why power had to be switched off while they were doing so.

"But instead of blaming customers for this, Connex and Thameslink should be considering why passengers acted as they did."

A Connex spokesman said: "We regret that customers were inconvenienced and we apologise for that, but it would have been far less serious if people had taken it upon themselves not to get off the trains."

A Thameslink spokesman said: "We don't like these situations any more than the customers and we apologise for the events which occurred that evening."