Facebook has suffered the most severe outage in its history, with key services rendered unusable for users globally for much of Wednesday, February 13, the BBC says.

The last time Facebook had a disruption of this magnitude was in 2008, when the site had 150m users - compared to around 2.3bn monthly users today.

Facebook's main product, its two messaging apps and image-sharing site Instagram were all affected.

The cause of the interruption has not yet been made public.

"We're aware that some people are currently having trouble accessing the Facebook family of apps," Facebook said in a statement.

"We're working to resolve the issue as soon as possible."

In response to rumours posted on other social networks, the company said the outages were not a result of a Distributed Denial of Service attack, known as DDoS - a type of cyber-attack that involves flooding a target service with extremely high volumes of traffic.

Estimates suggest the issue began around 16:00 GMT on Wednesday.

While Facebook's main service appeared to load, users reported not being able to post.

Those on Instagram were not able to refresh feeds or post new material. Facebook Messenger's desktop version did not load - but the mobile app appeared to allow the sending of some messages; however, users reported glitches with other kinds of content, such as images. WhatsApp, Facebook's other messaging app, had similar problems.