According to Jonathan Zdziarski, "messenger appears to have more spyware type code in it intended specifically for enterprise surveillance", the website motherboard.com reported.
"There is a lot of code that suggests Facebook is running analytics on nearly everything it possibly can monitor on your device," Zdziarski said in a twitter post.
After looking through the binary, Zdziarski said the app logs almost everything a user is doing.
A spokesperson for the social networking site, however, denied the claim.
"Privacy is core to our approach with Messenger and like any developer, we analyse usage trends to make our apps better, faster, and more efficient," the spokesperson told Gizmodo.