LONDON (BLOOMBERG) - Facebook agreed to suspend its planned use of data from UK users of its WhatsApp messaging service for advertising purposes, the nation's privacy watchdog said as it vowed to "keep pushing" so people get more control.

"We've set out the law clearly to Facebook, and we're pleased that they've agreed to pause using data from UK WhatsApp users for advertisements or product improvement purposes," UK Information Commissioner Elizabeth Denham said in a blog post Monday.

"We have now asked Facebook and WhatsApp to sign an undertaking committing to better explaining to customers how their data will be used."

WhatsApp's changes are the first steps by Facebook toward monetizing the platform since the social network's chief executive officer, Mark Zuckerberg, sealed a deal to buy the app for US$22 billion (S$30.5 billion) for the app in 2014.

European Union data protection regulators, who include the UK commissioner, last month said Facebook must stop processing user data from WhatsApp while they investigate the privacy policy changes the company announced in August. The Article 29 Working Party said on Oct 28 that it had "serious concerns" about the sharing of WhatsApp users' data for purposes that were not included in the terms of service and privacy policy when existing users signed up to the service.

A Facebook spokesman in London didn't immediately respond to an e-mail seeking comment.

"We think consumers deserve a greater level of information and protection, but so far Facebook and WhatsApp haven't agreed," the UK's Ms Denham said. "If Facebook starts using the data without valid consent, they may face enforcement action from my office."

The move, announced Aug 25, has also raised concerns with the United States Federal Trade Commission, which is reviewing a joint complaint from two consumer privacy groups filed in August claiming that Facebook's move violates US federal law banning unfair and deceptive practices.