A runaway train carriage slipped out of a washing shed, crashing through safety barriers and into trees, yards from the gardens of nearby homes.

The gleaming new South Central train overshot the end of the line as it rolled out of the sidings, careering through the buffers.

Neighbours watched in astonishment as the front coach skewed off the track, away from the main body of the train, and smashed into the surrounding trees.

No passengers were on the train but the incident, which damaged the front of the new Electrostar 375, is another embarrassment for bosses given the task of modernising the ailing railway service.

Investigators were last night downloading information from the train's black box in an effort to determine its speed when it hit the buffer.

The crash happened on a stretch of track at the Lover's Walk depot beside Millers Road, Brighton.

John Wilson, who lives in Millers Road, caught the drama on camera.

He said: "I woke up, looked out of the window and saw it.

"There is a siding and the train, which had obviously gone too far, broke the buffers, came on to the embankment and the first carriage was out of skew with the rest. I've never seen this happen before."

A spokesman for South Central said: "One of our new trains went through the buffers in the washing sheds and ended up in some trees. The front of the train was slightly damaged.

"It all happened within the confines of the depot and no passengers were involved. We are investigating."

The accident is the latest in a string of troubles for South Central since the first of its £856 million fleet of Electrostar 377 trains entered regular passenger service in December.

The company's 736 new units, introduced to replace its 40-year-old slam-door trains in Sussex, had to be modified after trial runs showed closing carriage doors could cause delays.

One of the distinctive green and yellow trains, complete with air conditioning, comfy seats, smart white tables and a top speed of 100mph, broke down on its fourth journey from Brighton to Seaford due to a technical fault.

In January the company revealed taxpayers would have to stump up for a delay in bringing hundreds of the trains into service when it emerged a power shortage from the rail lines meant they could remain out of action until 2006.