You might assume that chats sent on Facebook Messenger are completely private. But you'd be wrong.
Facebook confirmed Thursday that it uses automated tools to scan Messenger chats for malware links and child porn images. It also allows users to report chats that may violate community standards.
The company's moderators can review any messages that are flagged by users or the automated systems.
Facebook has long been clear that its workers can review posts to ensure they comply with its community standards. But many users had assumed their chats on Messenger were private.
Facebook said in a statement on Thursday that keeping messages private is its priority, but it also defended the automated tools as being "very similar to those that other internet companies use today."
"The content of messages between people is not used for ads targeting," a company spokesperson said. "We do not listen to your voice and video calls."
Facebook has come under intense scrutiny in recent weeks after news broke that Cambridge Analytica, a data firm with ties to President Donald Trump's campaign, may have had information on millions of Facebook users without their knowledge.
The episode has sparked questions over privacy on the social media platform, and led to calls for tough new regulation. It has also prompted calls for Facebook to be more transparent about how it handles user data.
Messenger, which allows users to chat amongst themselves, became a point of interest this week after Facebook CEO Mark Zuckerberg said the company had "detected" that "sensational messages" were being sent via Messenger in Myanmar.
Human rights advocates and journalists have made the case that Facebook was being used to spread misinformation in the country, adding fuel to ethic violence against a Muslim minority group called the Rohingya .
"In that case, our systems detect that that's going on," Zuckerberg said during an interview with Vox . "We stop those messages from going through."
Facebook clarified in a statement on Thursday.
"In this particular instance, a number of people reported receiving these messages which prompted us to begin investigating," a spokesperson said.
In recent weeks, Facebook has made changes to the platform and its policies regarding access to user data and transparency.
Facebook's data policy -- which was updated on Wednesday -- states that it collects "the content, communications and other information you provide when you ... message or communicate with others."
Zuckerberg also told reporters on Wednesday that the company could do a better job of explaining what it does with user data.
"[There are] many misperceptions about what we actually do," he said.
Zuckerberg is scheduled to face questions from two US congressional panels next week about how his company handles its users' data.