Home broadband connections are much slower than most suppliers advertise, a Which? report suggests.

The study found that while many packages now advertise speeds of 'up to' 8Mbps, the average speed for those connections was 2.7Mbps, and in one case was as slow as 0.09Mbps.

Only 30 per cent of customers were satisfied with their internet service provider, with some of the biggest names, including Orange, Bulldog and Tiscali, among the most poorly rated, Which? said.

Smaller providers fared better, with Global, Waitrose and Zen Internet all scoring more than 70 per cent in a customer satisfaction rating.

"It’s shocking that internet service providers can advertise ever-increasing speeds that seem to bear little resemblance to what most people can achieve in reality," Malcolm Coles, the editor of which.co.uk, said. "If it’s unlikely you’ll reach the advertised speed it should be made clear up front, so that you know with some certainty what you’re buying."

Mr Coles called upon Ofcom to investigate broadband providers to ensure that they weren't taking advantage of consumers.

Ofcom said that it was working closely with the Advertising Standards Authority (ASA) and would look at what measures could be taken if the level of complaints about broadband increased.

Last year the ASA ruled that broadband providers could only use the words 'up to' 8Mbps if a significant proportion of customers were likely to be able to achieve that speed.

Most providers now qualify the 'up to' claim with an acknowledgement that broadband speeds vary widely depending on, among other things, the distance from the local exchange and the characteristics of the phone line.

Which? tested the connection speeds of 27 ISPs in more than 300 households, and in a separate survey asked 14,642 of its members about the level of service their ISP provided.