The British government has been asked to inform the European commission (EC) of the situation regarding controversial ad targeting system Phorm by the end of this month.
Viviane Reding, commissioner for information society and media, has called on the government to detail whether Phorm's Webwise service contravenes European law, the BBC reports.
The system has sparked much debate over whether it breaks privacy laws in the UK as a result of a process whereby it tracks web users' internet habits and uses the data to deliver targeted ads on websites that sign up to the scheme.
Internet service provider BT has agreed to deploy the Webwise program on its network and is set to conduct a trial in the near future, while Virgin Media and TalkTalk will also make use of the system.
However, it was revealed earlier this year that the company had already conducted tests involving some of its broadband customers without their knowledge, although the UK information commission said it would not take action over this.
Foundation for Information Policy Research general counsel Nicholas Bohm said he thought European Union pressure could result in the UK information commissioner looking at Webwise again.
According to Phorm, Webwise offers benefits to consumers in the form of more relevant ads and built-in anti-phishing tools.