Facebook has acquired Kustomer, a startup specialising in customer-service platforms and chatbots, for a reported sum of $1 billion.

Kustomer was last valued at $710 million in a private funding round.

Facebook said late on Monday that Kustomer businesses will continue to own the data that comes from interactions with their customers.

"Facebook eventually expects to host Kustomer data on secure Facebook infrastructure," said Dan Levy, VP of Ads and Business Products.

In doing so, Facebook will act as a service provider at the instruction of business customers.

While Facebook will not automatically use Kustomer data to inform the ads that a user sees, businesses will have the option to use their data at Kustomer for their own marketing purposes, which may include separate advertising services on Facebook.

"Our goal with Kustomer is simple: to give businesses access to best-in-class tools that deliver excellent service and support," said Matt Idema, COO, WhatsApp.

Some 50 million businesses and 175 million people message a WhatsApp Business account every day.

This number is growing because messaging provides a better overall customer experience and drives sales for businesses.

"To that end, we recently announced several API updates for WhatsApp and Messenger, allowing for further integration into our partners' tools and faster onboarding to help businesses manage their communications with customers," Idema said in a statement.

Kustomer is an omnichannel CRM platform that brings customer conversations from various channels together into a single-screen view.