Nearly one-third of UK broadband users are unhappy with the connection speed they receive, it has been claimed.

According to figures from price comparison website uSwitch.com, 4 million out of the 15 million broadband subscribers are not satisfied with the speed of their connection.

Furthermore, lending weight to customers' annoyance, the survey also revealed that while the average advertised speed is pegged at 5Mb, in reality customers are receiving around 3Mb.

Steve Weller, head of communications services at uSwitch.com, said: "The ‘speed demons’ are the broadband companies still willing to let their customers to pay for an advertised broadband speed when they know full well it is impossible for them to receive it.

"It’s like selling a Porsche that will only go as fast as a Reliant Robin. Ofcom should go further than simply making suggestions to companies – it should be forcing them to be more transparent.

"The ASA (Advertising Standards Authority) also has an important role to play in cracking down harder on companies advertising speeds that many customers have no chance of receiving."