Car companies in the UK are smarting over the last minute postponement of a government-backed campaign to promote "greener cars". The launch of "Act on CO2" was scheduled for yesterday with an event in the Horse Guards Parade in London. But the event, involving car makers providing display models, was called off.

The aim was to provide a website where carbuyers could specify the kind of car and the price they were prepared to pay. They would then be shown the 10 cars with the lowest emission levels in their category.

A spokeswoman for the Department for Transport said the event had been postponed because of problems with the data for the website. "We had some technical problems. It is central to the campaign that we provide the right data." She said the aim was to launch the campaign as soon as possible.

"I think manufacturers would have been a lot more unhappy if the launch campaign had made mistakes. It would be very misleading if consumers were given the wrong information." Privately, however, automotive industry sources were furious at the last minute delay.

"It's a shambles. We were meant to have a month's notice about the data. In fact we had a day-and-a-half. It's a real mess," said one insider.