The European justice chief has fired a warning shot at Britain, following revelations that U.S. and U.K. spy agencies have developed capabilities to access personal information through smartphone apps such as Angry Birds.
Viviane Reding, the European Union justice commissioner, said that if reports of spies storing personal data from fibre optic cables inappropriately were true, she would take action against the country.
"Where there is no link to EU law, national security is an area of Member State competence. The hands of the Commission are tied," Reding said in a speech at the Centre for European Policy Studies in Brussels on Tuesday.
"But let me be clear. If I come across a single email, a single piece of evidence that the TEMPORA program (the U.K.'s electronic surveillance program) is not used purely for national security purposes, I will launch infringement proceedings. The mass collection of personal data is unacceptable."
She added that when she spoke to the U.K. about the nature of their surveillance programme, "the response was short: hands off, this is national security."
Smartphone app spied on
The comments follow reports that the U.S. National Security Agency (NSA) and the U.K.'s Government Communications HQ (GCHQ) were collecting information from smartphone apps about their users, according to secret documents revealed by former NSA contractor Edward Snowden to The Guardian newspaper, The New York Times and non-profit news organization ProPublica.
The GCHQ documents set out examples of what could be extracted from gaming, mapping and social media apps, including the popular Angry Birds game. Information the agencies could get from the apps included age, gender, location, and in some cases, sexual orientation, according to the reports.
In one document from 2008, the U.K.'s spy agency said that anyone using Google Maps on a smartphone was "effectively… working in support of a GCHQ system."
(Read more: NSA hacks Microsoft error messages: Report)
Video game developer Rovio Entertainment, which makes Angry Birds, said it did not "collaborate, collude, or share data with spy agencies anywhere in the world."
The NSA and GCHQ said they were working within the law, according to The New York Times and The Guardian.
Earlier this month, U.S. President Barack Obama set out a framework for reigning in the country's surveillance program through a series of limited reforms.
The EU has also been pushing for tougher data protection rules, and members of the European Parliament have called for a halt to a key EU-U.S. data sharing agreement.
Reding used her speech on Tuesday to outline reforms to the EU's data protection laws - the first in over a decade.
She said that EU-wide rules could be finalized before the end of the year. They include ways to implement tough fines on companies that break the rules, the right to request that your online data be deleted (known as "the right to be forgotten") and allowing users to decide how their data is used.
"I believe that this is a question of individuals' rights being overridden by technological change," Reding said. "That's why it is important to put individuals back in control by updating their rights."
—By CNBC's Arjun Kharpal: Follow him on Twitter @ArjunKharpal