WhatsApp will share user information with its parent company, Facebook, including phone numbers as the service explores options to boost its revenue. This will eventually result in businesses being able to send messages to users.

More than one billion people use the service and will be informed as of today as to changes in the app's terms and conditions.

Users will have the option to opt-out from their information being used for ad targeting on Facebook - but it is not possible to opt out of the messenger sharing information with Facebook in general.

"We want to explore ways for you to communicate with businesses that matter to you ... Whether it's hearing from your bank about a potentially fraudulent transaction, or getting notified by an airline about a delayed flight, many of us get this information elsewhere, including in text messages and phone calls," the company said in a blog post.

This data will be used to help targeted advertising on the main Facebook site and apps.

"We won’t post or share your WhatsApp number with others, including on Facebook, and we still won’t sell, share, or give your phone number to advertisers."

"Facebook can offer better friend suggestions and show you more relevant ads if you have an account with them. For example, you might see an ad from a company you already work with, rather than one from someone you’ve never heard of," WhatsApp continued.