Rail passengers faced new chaos today as cancellations and delays hit trains from Sussex to London.

And as commuters struggled in to work news emerged that another train has come off the rails, this time in Surrey.

Half today's trains from Brighton to London Victoria have been cancelled and the rest are subject to cancellation and delay because of speed restrictions.

The limits have been imposed while engineers carry urgent safety work following the Hatfield disaster, in which four people died.

Trains will leave Brighton for London only at 20 past the hour - and not at ten to the hour - throughout the day.

Services from London to Brighton will leave only at 38 minutes to the hour, and not at eight minutes past.

Several early evening trains have also been cancelled on the Brighton to King's Cross Thameslink line. Other services on this route are subject to cancellation and delay.

Railtrack expects reduced services, delays and cancellations to last for about two weeks while the speed restrictions remain in place.

Over the next couple of months, track replacement could be carried out on the Brighton-London route.

Work is likely to be carried out at weekends, so Saturday and Sunday services could face greater disruption.

Emergency repairs have begun today. Passengers can call 08457 484950 for further information on affected services or visit www.connex.co.uk/connex/fr_nexusbeta03.htm for details of Connex Express services.

A Railtrack spokesman said: "At the moment we have the worst case scenario because services will improve as repairs happen. We have the maximum amount of restrictions in place at the moment."

Predictably, many passengers are not amused by the disruption.

Student Chris Chrisanthos, of Norfolk Road, Brighton said: "I've been waiting here for ages. No one has said what's wrong.

"I'm not sure what's going on or when my train is going to leave. I'm not happy."

Katharine Parr, of Brighton, said: "I use the trains quite a lot. It's not the first time this has happened.

"The other day it took me two hours to get to London Bridge when it should take only one hour. It's a bit of a bummer.

"I only do this a couple of times a week. It would be a real pain if I did it every day."

Clare Saunders, of Ditchling Rise, Brighton, said: "The atmosphere down here is surprisingly calm. God knows what it would be like on a hot summer day with thousands of people milling around waiting for trains."

Meanwhile, two people suffered shock when a train came off the rails at Virginia Water, Surrey, this morning.

Railtrack said four coaches were derailed but remained upright and two people suffered shock-related injuries.

The train was the 0821 South West Trains service from Weybridge to Staines. It came off the rails at approximately 8.40am.

A Railtrack spokeswoman described the derailment as "not a massive incident".

It happened on the same stretch of track where a train travelling at 60mph ran into a bus stranded on a level crossing last week.

Railtrack said: "Provisional findings suggest the derailment was caused by adhesion problems between the train and the railhead.

"The train driver alerted the signalman as he approached Virginia Water that he was having difficulty stopping."