Facebook users say they are unable to use the app at the moment with people unable to see the newsfeed or comments.
DownDetector started receiving reports of problems with the site at around 5pm on Monday. Hundreds of Facebook users also took to Twitter to complain about problems using the social media site and app.
Some people said they cannot make comments and the newsfeed appeared to be down. Others said they could not look at their own, or favourite pages.