Broadband customers are still experiencing connection speeds less than half those advertised, with the worst offenders being 'high speed' products, a study suggests.

On average, broadband speeds were just 48 per cent of those advertised, with the figure falling to as low as 26 per cent for high speed packages offering connections of 8Mb/s or more, according to the study.

By contrast, customers on 2Mb/s packages experienced average speeds of 1.8Mb - or 88 per cent of the advertised amount, according to broadband-expert.co.uk, a price comparison website.

The study of 41,000 UK broadband connections found that on average, 8Mb/s packages delivered speeds of 3.4Mb/s - or 43 per cent of the advertised amount, with the worst offenders being Toucan and Virgin Media - whose customers experienced speeds 26 per cent and 29 per cent of those advertised respectively.

Among 16Mb/s or higher packages, Virgin's cable service was the fastest, but it still achieved an average of 10.4Mb/s - or 52 per cent of the quoted speed. Only one other provider - UK Online - achieved a speed greater than half that advertised.

The performance was stronger across the board in the 2Mb/s category, with Virgin, Talk Talk and UK Online all achieving slightly higher than the advertised speed. The weakest performers - Tiscali, Pipex, and Toucan - delivered 68, 70 and 73 per cent of their advertised speeds respectively.

"It seems clear that providers are promising speeds far greater than they are capable of delivering with top end packages," William Harvey, technical director of Broadband Expert, said. "If the internet service providers (ISPs) set a realistic expectation of the speeds that can be achieved, they are much less likely to upset consumers than those who advertise fast speeds and deliver less."

ISPs say they only advertise speeds of 'up to' a certain amount, and stress that the actual speed a customer will experience depend on a variety of factors, including their distance from the local exchange, and loading on the network. Several, including BT, also offer 'line checks' at the point of sale, so customers can gauge the likely speed of their home's connection.

Last year Ofcom, the regulator, called for providers to allow customers to try out connections before they signed up as part of an effort to ease what it called "widespread concern" among consumers who experienced slower than advertised broadband speeds.

In a letter to the six largest ISPs, including BT, Carphone Warehouse, Orange and Tiscali, the Ofcom Consumer Panel said: "People need to be able to see what they are buying, what influences the performance of the product, and how to do something about it."

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