South Central Trains admitted today there is a "high likelihood" expensive new rolling-stock will be left idle in sidings.

Group chief executive Keith Ludeman confirmed taxpayers would have to foot the bill for the delay in bringing hundreds of trains into use.

Earlier this month, it emerged the trains could remain out of action until 2006 because of a power shortage on South-East rail lines.

South Central, which operates most train services in Sussex, has ordered 736 new carriages to replace its 40-year-old slam-door trains.

But only 42 are being used because the power supply desperately needs upgrading.

The new carriages - with air conditioning, sliding doors and computerised controls - are heavier and consume more power than the electricity supply can provide.

Giving evidence to the House of Commons transport committee last night, Mr Ludeman said the firm was looking at ways of preventing trains lying idle.

These include trying to delay the date the trains are due to be delivered by manufacturers.

But he admitted: "There is a high likelihood trains will be sitting in sidings with nowhere to go.

"All we can do is work with my industry colleagues so we do not have a situation where large numbers of trains are sitting in sidings not being used."

Mr Ludeman insisted there was nothing his company could do to solve the power supply problem.

He said the responsibility rested solely with the Strategic Rail Authority (SRA), which needs a massive government grant to carry out work to upgrade the network.

He confirmed that, in the meantime, the cost of meeting payments for the trains during the delay would be met by the SRA.

Gwynneth Dunwoody, chairman of the powerful select committee, asked Mr Ludeman if this meant the taxpayer and he replied: "Yes".

In a 30-minute evidence session, Mr Ludeman revealed trains are significantly more overcrowded in the morning rush hour than at night.

Commuter routes from Sussex to London suffer 11 per cent overcrowding in the morning, but only one per cent at peak times in the evening.

Mr Ludeman added: "I do not know what the attractions around Victoria are, but they do take a long time to come home."

He also confirmed the company was looking at plans to run 12-carriage trains from Brighton to London.

At present, platforms at some stations are too short to cope with trains of this length.

But Mr Ludeman said a device was being investigated which would read platform lengths and allow selective door-opening.