Most ADSL broadband users in the UK can only achieve half the download speeds promoted in ISPs' ‘up to 8Mbps' adverts, according to an Ofcom study.

What's more, the communications regulator's research reports that the highest download speed someone with an 8Mbit/s package can achieve is actually 7.2Mbit/s.

The figures have been released following an Ofcom study earlier this year based on 60 million performance tests in 1,600 homes.

According to the research, less than 10 percent of households on ‘up to 8Mbit/s' deals could receive 6Mbps or more in practice, while 20 percent had to make do with less than 2Mbit/s. The average download speeds achieved in April were 4.1Mbps. However, this was an improvement on January, when average speeds were 3.7Mbit/s.

The study also highlighted the broadband slowdown in rural areas. Ofcom said average speeds were 4.6Mbps in urban areas, compared with 3.3Mbit/s in rural areas.

There was good news for Virgin Media, however. Ofcom said average speeds on the company's ‘up to 10Mbit/s' cable broadband network were between 8.1Mbit/s and 8.7Mbit/s, twice that achieved by ADSL users.

"As the Ofcom speed tests show, Virgin are the best bet for a package that delivers on speed and this is a result of significant investment in their network," said James Parker, broadband manager at MoneySupermarket. "People need to check how their providers fare when picking a broadband package, as the Ofcom test shows, the faster products can often be poor value for money."