Facebook, one of the world's most popular social networking sites, has crashed.

The outage was reported around the world; in countries including Thailand, Hong Kong, Australia, Japan and Holland.

The crash happened at around 9am, with the Facebook blue branding displayed alongside the message "Sorry, something went wrong".

The problem also affected the Facebook apps.

By 9:20am, the site refused to load at all - with the message "service unavailable" shown on a white background.

Users got this message earlier

However, by 9:30am users reported the site was functioning again.

Facebook crashed in the US in February this year, after previously going offline for four hours in October last year due to network maintenance.

Facebook has 1.3 billion monthly active users, making it one of the most popular websites in the world.

It is listed on the NASDAQ stock exchange in the US. Its shares were trading up yesterday, as US markets will not open until later.

The outage is expected to have cost the website hundreds of thousands of dollars.