Facebook has since apologised for the gaffe, telling AAP that the issue was now completely resolved.
"Earlier today, an internal issue in our web infrastructure caused the site to be slow or unavailable for a brief period of time," a Facebook spokesman told AAP.
"We resolved the issue quickly, and should now be back to 100 per cent. We apologise for any inconvenience."
Facebook did not elaborate on the nature of the internal issue and didn't provide any further details.
Messages posted online, purportedly linked to the hacking collective Anonymous, claimed responsibility for attacking the site.
Meanwhile Facebook has also come under fire for unintentionally blocking popular secure web browser Tor (short for The Onion Router), a browser used highly in places with strict internet censorship.
Tor has however posted that Facebook is not intentionally blocking Tor.
"A high volume of malicious activity across Tor exit nodes triggered Facebook's site integrity systems which are designed to protect people who use the service. Tor and Facebook are working together to find a resolution," the post read.