One of the firms maintaining the London Underground is having to buy spare parts on auction website eBay because the equipment is so old, it was revealed yesterday.

Tubelines, the consortium which manages the Jubilee, Northern and Piccadilly lines, has bought computer cards, old chips and other equipment which is now out of stock.

Company officials said they had resorted to the internet because some of the signalling system on the Tube was so old.

"We need to make sure we have appropriate supplies," said a spokesman. "In some cases we have cloned equipment but where parts and other pieces of equipment are out of stock we will buy them."

Some of the items already bought on eBay were 10 to 20 years old, it was revealed.

"It highlights the need to upgrade the system," added the spokesman for Tubelines, which is made up of Amey, Bechtel and Jarvis.

A problem with cab radios continued to cause huge delays for travellers on the Northern line today, with services cut by up to 40%.

The ageing cab radio system is due to be replaced next year.