WASHINGTON: U.S. regulators have warned Facebook and WhatsApp to uphold the data privacy of their users, following the announcement of their $19 billion merger.

In a letter to both Facebook and WhatsApp, the Federal Trade Commission said that WhatsApp has made clear privacy promises to consumers, and that both companies have told consumers that after any acquisition, WhatsApp will continue its current privacy practices.

"We want to make clear that, regardless of the acquisition, WhatsApp must continue to honour these promises to consumers," the FTC said and warned the two companies that anything other than this would be considered to be in violation of the U.S. laws.

In 2011, Facebook settled FTC charges that it deceived consumers by failing to keep its privacy promises.

Under the terms of the FTC's order against the company, it must get consumers' affirmative consent before making changes that override their privacy settings, among other requirements, an official release said.

The FTC letter notes that before making any material changes to how they use data already collected from WhatsApp subscribers, the companies must get affirmative consent.

In addition, the letter notes that the companies must not misrepresent the extent to which they maintain the privacy or security of user data.

The letter also recommends that consumers be given the opportunity to opt out of any future changes to how newly-collected data is used, FTC said.

After the acquisition of WhatsApp, Facebook CEO Mark Zuckerberg had promised its users that there will be no change in their service, neither there will be any add.

"Here's what will change for you, our users: nothing... And you can still count on absolutely no ads interrupting your communication," he wrote.

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