The mobile messaging service Whatsapp is going to start sharing users' phone numbers with Facebook, meaning "better friend suggestions" and "more relevant ads".

The move is WhatsApp's first update to its privacy policy since it was acquired by Facebook in 2014.

Whatsapp is also exploring ways for users to communicate with businesses "that matter to you too".

It could mean hearing from your bank about a potentially fraudulent transaction or getting notified by an airline about a delayed flight via the messaging service.

Whatsapp said it will be testing these features over the coming months.

However company bosses sought to reassure users that their phone numbers will not be shared or posted on social media.

"Not WhatsApp, not Facebook, nor anyone else," it said in a blog post.

"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," it added.

Whatsapp also said the closer integration with Facebook will enable it to "better fight spam".