Internet service provider (ISP) Zen has announced that it will be offering a free upgrade to all new and existing broadband customers.

Over the coming months, users subscribed to a line with the broadband supplier can expect to see their download speeds increased to 20Mb and their uploads boosted to 1Mb.

The ISP is to begin rolling out the speed upgrade, which has been in the pipeline since 2008, this summer, although it warned that some customers may have to wait until 2010 to see the benefits.

Aside from the speed increase, everything else will remain the same on all of its broadband packages.

"The final phase of tests and trials for these new faster services is due for completion this summer," explained the ISP's Head of Product Management Andrew Saunders.

"We are retaining our current monthly contracts and just want customers to enjoy the benefits of our new faster services at any time of the day, with no gimmicks or restrictions hidden in a fair use policy."

Earlier this year, Zen was granted a "Best Buy" rating from consumer magazine Which?, receiving five stars for its customer service levels.