Social media websites Facebook, Instagram, Tinder, Hipchat and AIM suffered unexplained outages early Tuesday (GMT). Notorious hacking group Lizard Squad has claimed responsibility for the crash, according to a tweet. The tweet, sent from the group's Twitter account, read: "Facebook, Instagram, Tinder, AIM, Hipchat #offline #LizardSquad". Facebook and Instagram have denied that their websites were attacked, instead citing "systems change" as the cause of the unusual outage.

Millions of people from all over the world were unable to access their accounts and personal data on some of the world's largest social networking websites. Facebook suffered a rare outage, and those using the Facebook website were greeted with a blank page. Users of the Facebook Android app were unable to update newsfeeds or access their data. Instagram, which is owned by Facebook, was also unresponsive, along with dating app Tinder and chat service HipSter. 

Just hours before Lizard Squad appeared to take responsibility for the unprecedented social media outage, the hacking group also claimed that they had hacked the website of Malaysian Airlines. They also claimed responsibility for hacking the Microsoft's XBox Live Network and the Sony PlayStation Network in December last year. The group allegedly aligns itself with the internationally recognized terrorist organization, Islamic State of Iraq and Syria (ISIS).

Facebook has outrightly denied that its website was hacked, instead maintaining that its engineers were the cause of the problem. A Facebook spokesperson told the media: "This was not the result of a third party attack but instead occurred after we introduced a change that affected our configuration systems. We moved quickly to fix the problem, and both services are back to 100% for everyone." It also denied that any external group was responsible for the 50-minute outage.

Instagram had initially acknowledged on Twitter that its website was down. The tweet, which read "We're aware of an outage affecting Instagram and are working on a fix. Thank you for your patience." was subsequently deleted. Tinder has not made any official comment on the outage, but it is believed that the collapse of its systems, which are interconnected with those of Facebook, was triggered by Facebook outage.