Twitter is back up for most users in Britain, Canada, the U.S. and several other places across the globe, after the social media site was inaccessible earlier in the day, Thursday, only one day before the 2012 Olympic Games begin.

The social network’s main website was down in New York, London and Johannesburg, and either sluggishness or outages were reported in North America, Europe, Asia, Latin America, the Middle East and Africa.

A spokeswoman for Twitter said staff had been looking into the issues but she would not elaborate on the nature of the problem.

Updates on the London Olympics from sports fans are expected to flood Twitter starting Friday. At a recent European Championship final, the network’s users fired off more than 15,000 tweets per second, setting a sports-related Twitter record.