THE British arm of Ebay, the online auction site, has signed up its ten millionth registered user, and is pushing for further growth with a new pitch to potential business customers.

The number of Ebay users has doubled in less than a year. On its fifth birthday in October, the UK website had 7.6m users — suggesting it is attracting another 600,000 every month.

Doug McCallum, managing director of Ebay UK, said there were still “enormous opportunities” for growth. The “gigantic” second-hand markets for cars and for business, office and industrial equipment are worth “trillions”, he said.

Ebay is making it easier for businesses to use its site by allowing conventional banking arrangements and providing dedicated customer support. Previously, companies had to enter a credit-card number if they wished to trade.

IBM and Sun Microsystems, the computer companies, already use Ebay to offload equipment they receive back from their customers. Vodafone has also used the site to sell mobile phones.

McCallum said hundreds of independent car dealers were using Ebay, and the company is keen to encourage many more to do so.

He said: “The area in which we have the greatest traction is cars, motorbikes and automotive parts. Our growth is extraordinary, but still we have only a tiny penetration of the second-hand vehicle market.”

Ebay had fewer than 1m users when McCallum joined the company in December 2001. “We are excited about crossing the 10m-user milestone,” he said. “We have a member in more than half of Britain’s households.”

The UK business is one of the biggest outside Ebay’s American homeland, with the value of goods traded exceeding $1 billion. However, the company’s latest results, announced by chief executive Meg Whitman two weeks ago, disappointed Wall Street investors, who were concerned at the first signs of slowing growth.