Wikipedia has joined online retailer Amazon and other large online firms in rejecting Phorm's Webwise service, which tracks users' activities and sends them targeted advertising.
The Wikimedia Foundation, which runs Wikipedia, has requested that all the domains under its control be excluded from scanning by the Phorm Webwise system.
"We consider the scanning and profiling of our visitors' behaviour by a third-party to be an infringement on their privacy," the Wikimedia foundation said in a blog posting.
Amazon's decision to stop the intrusive online tracking service from using the Amazon website could mark a turning point, commentators said last week.
The Open Rights Group (ORG), which has called for Webwise to be banned, has welcomed the response from the online industry.
"We would like to thank Wikipedia and Amazon for prioritising their users' privacy and taking this stand. We hope Facebook, AOL, Bebo, MSN, Google and others can follow their lead," said Jim Killock, executive director of the ORG in a blog posting.
Opposition from privacy groups has delayed full UK implementation of the Phorm technology. Only a limited trial with 10,000 BT customers has been conducted in the UK.
Virgin Media and Carphone Warehouse have also signed deals with Phorm, but no trials have been announced.
At the end of March, Phorm announced plans to conduct the largest trial of its controversial technology with its first customer outside the UK.
The deal with South Korean broadband provider KT will give Phorm the opportunity to prove its technology on one of the world's most advanced networks
The future of behavioural targeting technologies such as Phorm's is uncertain in Europe, where officials could rule that consumer profiling by advertisers breaches privacy laws.
Last week the European Commission (EC) began proceedings against the UK over the use of Phorm.