Users of the Facebook Messenger app don't know they're allowing Facebook to spy on them, a new report revealed.

The terms and conditions stated in the app allow this, said a story in the Huffington Post, the liberal U.S. online news aggregator.

Users know every app has its own terms and conditions but very few actually read them. Messenger's conditions allow Facebook to access its users' mobile phones without their knowledge.

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Reports say over one billion Facebook Messenger users ignore the lengthy and tedious terms and conditions. Unfortunately, the app has control over a user's personal and private data once a user accept the terms.

The "spying" does not end with Facebook accessing information on the other apps users install on their devices. Apparently, Facebook also has the "right" to change the device's network connectivity.

Messenger also has the right to call phone numbers in the user's directory "without your intervention," which means Messenger can call a user's contacts and cause unexpected charges.

The terms also state Facebook will have access to the user's SMS messaging. Just like the unlimited access to the user's directory, Facebook can also send messages without user's permission.

They can also use your device's microphone to record audio "at any time without your confirmation."

Aside from the mic, they also have access to the user's camera and can take and record pictures and videos, again, "without your confirmation."

Phone logs, incoming and outgoing calls, and emails are also included in the access users provide the app.

Facebook previously received criticism about its privacy when it conducted a psychological experiment on almost 700,000 users without their knowledge.

Facebook manipulated the newsfeed of these users by sending sad posts to half of them while the other half got positive posts to see how "emotional contagion" could influence a person.

Facebook said that the research was conducted to "improve their services."

Facebook has a negative history when it comes to protecting the privacy of its user's information. 

TagsFacebook messenger app