Local testing indicates that there has been no outage of Facebook, Messenger or WhatsApp in either Australia or New Zealand.
The outage appears to have struck around two hours ago (8:30pm Sunday, eastern Australian time) and is yet to be resolved.
This follows a severe outage a month ago that was blamed on a misconfigured server.
Screenshot image from downdetector.com
Updates will be provided as they become available.
Update (6:45am EST). All properties seemed to return to service around midnight. Still no indication from Facebook as to the cause.