A third of the UK now has access to broadband connections with speeds of 'up to' 100Mbps, says Virgin Media.

The ISP revealed its superfast fibre network has been extended to Harborne in Birmingham, Lincoln, Seven Kings in Greater London and Solihull - giving around 20 million Brits access to the service, which was first launched last year.

Virgin Media added that by mid-2012 it hopes its entire network, which serves around half of the country, will be upgraded to offer speeds of 'up to' 100Mbps.

"We're very proud to reach another significant milestone in our broadband history as we play a leading part in the development of the UK's next generation infrastructure. But delivering faster speeds so that consumers can enjoy all the benefits of this rapidly growing connected world is not enough if the industry doesn't deliver on its marketing claims," said Jon James, Virgin Media's executive director of broadband.

"This [up to 100Mbps] is the sort of connectivity that can give families access to the best in digital entertainment and online services in an instant as well as provide the foundation for business growth and start-up Britain. We've successfully proven we can achieve speeds of 1.5Gbps – some of the fastest broadband in the world – so we're ready for when consumers want more in the future as we expect demand will continue to accelerate."

However, James also revealed that despite new guidelines designed to clamp down on the use of 'unlimited' and 'up to' in broadband advertising being issued last month "there remain too many adverts which don't meet even that low threshold".

The guidelines, which were issued by the Advertising Standards Authority, state that any maximum speed claims used in broadband advertising must be based on actual experience of users and ISPs must be able to demonstrate these speeds can be achieved by at least 10 percent of its customers.

"The new guidance was welcome but we publish the typical real world speeds our customers get. Doing less gives the industry, and broadband, a bad name so we're urging other ISPs to follow suit," he said.