Facebook users faced problems accessing the social network in many countries across Europe for about two hours on Wednesday due to “technical difficulties”.
Facebook smartphone and tablet apps were also affected, as users reported on Twitter.
The company apologized for the incident and said the issue was now resolved.
“Today we experienced technical difficulties causing the site to be unavailable for a number of users in Europe,” Facebook said in a statement.
“The issue has been resolved and everyone should now have access to Facebook. We apologize for any inconvenience.”
More isolated accounts of inaccessibility were posted by users in further afield places such as Pakistan and South Korea.
Facebook has about 850 million users worldwide and many took to Twitter to share information about the down time, with “#facebookdown “quickly becoming a trending topic on the microblogging site.
Most took a humorous view, with user @Purple_Cow tweeting: “#Facebook is #down, expect a surge in productivity in offices everywhere today.”
However, some website owners who make use of the Facebook Connect service – which allows people to log into external sites by using their Facebook account – were left frustrated by the technical issues.
Launched in February 2004, last month Facebook announced plans to float on the stock market. It seeks to raise $5 billion from the move, making it the biggest sale of shares by an internet company.