The company also said it was considering whether to refund advertisers for lost exposure due to the problems, which internet outage trackers showed affected users in Europe, Japan, North and South America.
A company spokesperson said that a server configuration issue made it difficult for people to access apps and services, and that Facebook is still investigating the overall impact of the outage and is considering issuing refunds for advertisers.
Media reports earlier said millions of users were affected, and thousands took to Twitter on Wednesday (March 13) and Thursday (March 14) to complain under the hashtag #facebookdown
Facebook takes tens of millions of dollars of advertising revenue every day.
(Produced by Aleksandra Michalska)