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

The last time Facebook had a disruption of this magnitude was in 2008, when the site had 150m users - compared with 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.

Facebook's apps seemed to be recovering on Thursday morning, with Instagram announcing it was back.

"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.

An NBC News broadcaster reported the cause was related to "overloaded" databases.

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.

A third-party outage map suggested the problem was global - DownDetector monitors posts on other social networks for users mentioning a loss of service elsewhere.

The issue also affected Facebook Workplace, the service used by businesses to communicate internally.

Buenos Aires-based designer Rebecca Brooker told the BBC the interruption was having a significant impact on her firm's work.

"Facebook for personal use is fine - but what happens when we rely on large companies such as this to provide business services?" she said.

"I'm trying to communicate with my team in New York. Facebook Workplace is our only channel for [communication] with the exception of email." (BBC)

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