Adverts are set to become a global fixture across Facebook’s (FB) Messaging app, following the conclusion of promising tests with users in Australia and Thailand.

In an online post, the social media network, which already enables firms to send sponsored content to subscribers who had previously been in contact with them, confirmed that it will steadily start to sell advertising space across its Messaging service in the coming weeks. The plan is to begin with a small percentage of users.

The company added that marketing material will appear in the main inbox tab between chat threads, meaning that they won’t be shown in conversations. When users click on the ads they will be either taken to the advertiser’s website or a chat window.

Marketing firms, which are expected to be keen to capitalize on this new opportunity to advertise products to Facebook Messenger's 1.2 billion monthly users, will be able to buy ads via the company's dedicated ad manager. According to VentureBeat, ads will be specifically designed to target each individual user, similar to how they function on the rest of the website and Instagram.

Facebook’s move to extend advertising to its Messaging service appears to be a no brainer. The social media network’s ad revenues rocketed 57 percent to $26 billion in 2016, providing a lucrative source of income to a business that otherwise struggles to make much money. (See also: How Does Facebook Make Money?)

“[Advertising is] not necessarily everything, but it’s definitely how we’re going to be making money right now,” Messenger head of product Stan Chudnovsky told VentureBeat. “There are some other business models we are exploring as well, but they’re all around ads one way or another.” (See also: Facebook Ad Revs Likely to Surprise for 2H17: CS.)

On the flip side, Facebook’s latest advertising push could risk irritating the website’s users. A recent article published by TechCrunch believes this to be the case, pointing out that the ads are huge and, as a result, tend to interrupt user experiences.