Facebook has crashed. It's not yet known why or how many people this has affected.

Social media giant Facebook is back online after experiencing technical difficulties across the globe.

The site crashed about 1.20pm on Tuesday and was back up shortly before 1.50pm.

It was unclear what had caused the error and how many people were affected.

DOWNDETERCTOR.COM The map shows the affected areas.

However, users in New Zealand and across the world reported issues with loading the social media site.

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A map on downdetector.com showed the affected areas to be New Zealand, Australia, parts of Asia and North America.

When users tried to load the site they were met with a generic error message saying "something went wrong".

It went on to say: "We're working on it and we'll get it fixed as soon as we can."

The hashtags #facebookdown and #facebookisdown were gaining traction of Twitter within 10 minutes of the crash.

The site was back up and running within 30 minutes but it was long enough to cause a stir online.

As of March 2017, Facebook had 1.94 billion monthly active users, according to Facebook.

During March, the site had an average of 1.28 billion daily active users.

A Facebook spokesman said the error had been fixed.

"Earlier today some Facebook users were unable to access Facebook briefly. We've now fixed the issue and apologise for the inconvenience caused," he said.