Heavy traffic and an unidentified problem have taken Twitter offline on the eve of the Olympics, The Telegraph reports.
The company posted an update on its blog at 4.43pm on Thursday, July 26 saying "Users may be experiencing issues accessing Twitter. Our engineers are currently working to resolve the issue."
Users immediately took to Facebook, with some identifying the first problems at 4.30pm. The site did not respond to initial requests for comment.
Services were largely restored by 5.15pm. On its software developer website, Twitter however still listed service disruptions for features including user statuses, user search, friends lists and showing users who follows them and who they follow.
Last month Twitter blamed a "cascading bug" for the outage which also drove frustrated users to other social media sites to complain.
Mazen Rawashdeh, Twitter's vice president of engineering, said at the time of the original outage "It’s imperative that we remain available around the world, and today we stumbled. For that we offer our most sincere apologies and hope you’ll be able to breathe easier now."
He said that engineers found a "cascading bug with one of our infrastructure components". Mr Rawashdeh added: "A 'cascading bug' is a bug with an effect that isn’t confined to a particular software element, but rather its effect 'cascades' into other elements as well.
"One of the characteristics of such a bug is that it can have a significant impact on all users, worldwide, which was the case today. As soon as we discovered it, we took corrective actions, which included rolling back to a previous stable version of Twitter."
Shortly after Twitter first went down a hacker claimed responsibility for taking the site down. 'Cosmo The God' said: "We just took down twitter.com with a DDoS Flood, its been down for 30minutes now."
Cosmo is linked to the hacking group UG Nazi, which has previously claimed attacks on a number of websites including CIA.com, CloudFlare and BP.com.
Twitter later denied that the outage was related to activity by hackers.
