WASHINGTON (REUTERS, BLOOMBERG) - WhatsApp, Facebook Inc's popular messaging service, will start sharing users' phone numbers with its parent, allowing for more relevant advertisements and friend recommendations on the social network.

The move is WhatsApp's first update to its privacy policy since it was acquired by Facebook in 2014 for US$19 billion (S$25.7 billion).

WhatsApp will also explore ways for businesses to send messages using its platform over the next several months, it said in a blog post on Thursday (Aug 25).

The messages could include appointment reminders, delivery and shipping notifications or marketing material, the company said in its revised terms of service.

In the blog post, WhatsApp said it will be testing these business features over the coming months.

The strategy is an important step for Facebook as it attempts to make money from its most expensive acquisition.

Facebook's other texting platform, called Messenger, also has been attempting to court businesses as a way to generate revenue. Several services in Asia, most notably WeChat in China, have successfully taken this approach.

WhatsApp also reiterated on Thursday its commitment to encryption, saying no outside parties are able to see what its users are saying to each other.

The policy has put the company at odds with government authorities in the United States and Europe who want an ability to intercept the communication of potential terrorists.

"Our belief in the value of private communications is unshakeable," the company said.