Hackers targeted La Liga giant Barcelona and the Olympic Games movement on Saturday as their Twitter accounts were attacked.
The OurMine group posted messages on multiple accounts belonging to Barcelona and the International Olympic Committee.
Barcelona have accounts in several languages and relating to various aspects of the club, including its La Masia youth academy, and all appeared to have been hacked.
The hacking incident came soon after Barca beat Getafe to join Real Madrid on 52 points at the top of La Liga.
Each account sent out the message: "Hi, we are OurMine. Well, this is the second time, the security level is better but still not the best to improve your accounts security."
The OurMine group previously hacked Barcelona's Twitter in 2017, falsely claiming the club would be signing Angel Di Maria from Paris Saint-Germain.
Barcelona acknowledged the latest cyber security breach after taking back control of its accounts, posting: "FC Barcelona's Twitter accounts have been hacked, which is why messages from outside our club have appeared, and which have been reported and deleted. The tweets were made through a third-party tool for data analytics.
"FC Barcelona will conduct a cybersecurity audit and will review all protocols and links with third party tools, in order to avoid such incidents and to guarantee the best service to our members and fans. We apologise for any inconvenience this situation may have caused."
The Olympic Games accounts were similarly attacked.
Messages from OurMine were posted across its official accounts, including those for the Olympics, Athlete365 and IOC Media, before being deleted.
The hacker group has previously targeted such organisations as WikiLeaks, Real Madrid, the NFL and its teams, Facebook, Instagram and the New York Times.
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