• A photographer snaps a photo of the Facebook logo at the Facebook Innovation Hub on February 24, 2016 in Berlin, Germany.

A photographer snaps a photo of the Facebook logo at the Facebook Innovation Hub on February 24, 2016 in Berlin, Germany. (Photo : Getty Images/Sean Gallup)

Facebook has started testing their ads on Messenger for users in Thailand and Australia. Once the tests are considered successful, the social network giant will be rolling out the service globally.

Most of the ads look similar to the ones also found in Instagram. They appear to be a small image coupled with a line or two of text on the bottom. If the user taps on them, they will be led to the advertiser's site or app.

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Ads will not appear while users are chatting with their friends. Facebook presents the ads in Messenger's home screen where users search for the conversations with their friends, Tech Crunch reported.

For those users with smartphones that have large screens, it might not be a problem. Users with smaller devices, however, may find it difficult to browse through their conversations with the ads.

Users can also choose to start a chat conversation with the brands if it is available. Facebook Messenger chat bots are slowly growing in number to help businesses take care of their customers on social media even if they are not actually online to answer queries and such.

Messenger head of product Stan Chudnovsky said in a statement obtained by Recode that the company did not want to invade user privacy. That is one reason why they wanted to try it out in a smaller number of users first.

"Originally, people were also not very big believers in ads in News Feed because that felt very private too," said Chudnovsky. "But the playbook that we had is the same we are worried about [that] but we are also testing things even when we are worried about them.

Facebook Messenger users in other countries outside Australia and Thailand should not worry for now. Chudnovsky said that the company will be conducting long-term tests which means it can take months before they can finish.

Find out more Messenger features below: