European privacy watchdogs have sent letters to Facebook's WhatsApp over its sharing of information with parent company and Yahoo over a 2014 data breach and its scanning of customer emails for U.S. intelligence purposes. According to the information which has been provided to users of the service, WhatsApp will share information within the "Facebook family of companies" for a range of purposes that include marketing and advertising.

"These are not purposes which were included within the Terms of Service and Privacy Policy when existing users signed-up to the service. These changes have been introduced in contradiction with previous public statements of the two companies ensuring that no sharing of data would ever take place," reads the letter sent by the European Union data protection authorities.

The authorities said they had serious concerns about WhatsApp's recent change in privacy policy.

The authorities, known as the Article 29 Working Party, "requested WhatsApp to communicate all relevant information to the Working Party as soon as possible and urged the company to pause the sharing of users' data until the appropriate legal protections could be assured."

WhatsApp said the company was working with data protection authorities to address their questions.

"We’ve had constructive conversations, including before our update, and we remain committed to respecting applicable law," she said.

The watchdogs also wrote to Yahoo over a massive data breach that exposed the email credentials of 500 million users, as well as its scanning of customers' incoming emails for specific information provided by U.S. intelligence officials.

They asked the company to communicate all aspects of the data breach to the EU authorities, to notify the affected users of the "adverse effects" and to cooperate with all "upcoming national data protection authorities' enquiries and/or investigations.

The Yahoo and WhatsApp cases will be discussed by regulators in November.