Instant messaging giant WhatsApp, which boasts more than one billion users around the world, is going to begin sharing limited user data — including users' phone numbers — with parent company Facebook.
"Even as we coordinate more with Facebook in the months ahead, your encrypted messages stay private and no one else can read them," WhatsApp said in the blog post. "Not WhatsApp, not Facebook, nor anyone else."
The company added that it would not post or share users' WhatsApp number with other entities, including Facebook "and we still won't sell, share, or give your phone number to advertisers."
WhatsApp said sharing phone numbers with Facebook would let the company offer better friend suggestions or show users more relevant ads in their Facebook accounts. The company added that "coordinating more with Facebook" would allow WhatsApp to better track metrics about how people use their services and fight spam.
In April, WhatsApp expanded its privacy protections to include end-to-end encryption in the latest version of its app so that only the sender of a message and its recipients were able to see what has been said. Facebook acquired the company in 2014 for $19 billion.
The company's founder, Jan Koum, has long been a proponent for strong encryption and security protections. Koum was among several high-profile tech CEOs who came out in support of Apple when the company denied the FBI's request to create a way to hack the iPhone of the San Bernardino shooters.
Koum said in a post on Facebook in February he had "always admired Tim Cook for his stance on privacy and Apple's efforts to protect user data."
"We must not allow this dangerous precedent to be set," he said in the post. "Today our freedom and our liberty is at stake."
Existing users will have 30 days to opt out of WhatsApp sharing the account information with Facebook after accepting the new terms and policies by going to their account settings, according to the legal information section of its website.
The company said the changes were also part of plans to "test ways for people to communicate with business in the months ahead" without experiencing third party banner ads or spam.
On the Frequently Asked Questions section of its website the company said it was looking to explore communications between users and business such as orders, transactions, appointment information and delivery notifications.
The company added that "messages you may receive containing marketing could include an offer for something that might interest you."
Some privacy advocates have criticized WhatsApp's move to share the data with its parent company.
"This is a strong-arm tactic on the part of Facebook," Jeff Chester, executive director of the Center for Digital Democracy in Washington, D.C., told the Associated Press "They continue on a campaign on to run roughshod on our privacy rights."