BT has reportedly halted plans to deploy the hugely controversial Webwise ad tracking system from UK outfit Phorm.

The unconfirmed public statement leaves the door open to future use, but given the spending constraints currently piled on the telecom company, that could rule out its use for some time.

"We continue to believe the interest-based advertising category offers major benefits for consumers and publishers alike," said a BT spokesman, quoted by the Guardian newspaper."However, given our public commitment to developing next-generation broadband and television services in the UK we have decided to weigh up the balance of resources devoted to other opportunities."

"Given these commitments, we don't have immediate plans to deploy Webwise today. However, the interest-based advertising market is extremely dynamic and we intend to monitor Phorm's progress ...before finalising our plans," the statement continued.

The decision appears to put into the deep freeze a trial that began in secret three years ago as a way of serving ads to the ISP's customers based on their web usage. Contentiously, BT's first 2006 trial tracked behaviour without informing the roughly 20,000 customers involved which led to claims that Phorm was being used as a spyware system in ways that violated the UK Data Protection Act.

More recently, the usually prickly and still loss-making Phorm launched a PR campaign to reform its image, launching an add-on to Webwise called Webwise Discover, a search tool for ‘recommending' websites to users based on their previous browsing habits. The launch was seen as an attempt to rebrand the ad tracking system in ways that could be useful to ordinary web users and not just companies such as BT, and Phorm itself.

Phorm still has two large ISPs testng its system, Virgin Media and TalkTalk, but it is a certainty that if either one deployed the system it would be on an opt-in basis, which raises doubts about its probable reach. It is likely that negative publicity would encourage large numbers of users to ask to be excluded from a system whose overriding purpose is to serve annoying advertisements.