LONDON, England (AP) — Twitter blamed systems failures — not a crush of traffic around the Olympic games — for an outage yesterday that saw people around the world experience problems accessing the micro blogging site for more than an hour.

The San Francisco-based company said the outage was caused by a "noteworthy" double failure in its data centres. When one system fails, a parallel one is meant to take over, but two systems coincidentally stopped working at around the same time, Twitter said.

"I wish I could say that today's outage could be explained by the Olympics or even a cascading bug," Mazen Rawashdeh, VP of engineering, said in a statement apologising to users. "Instead, it was due to this infrastructural double-whammy."

He apologised for giving its users "zilch" instead of the service, saying the company is "investing aggressively" in its systems to avoid a repeat situation.

Visitors to the site yesterday were greeted with a half-formed message saying that "Twitter is currently down." The fields where a reason for the outage and a deadline for restoring service were apparently meant to go were filled with computer code.

Sluggishness or outages were reported for more than an hour in countries in the Americas, Europe, Asia, and Africa. Some users were able to post updates through their phones or third-party applications.

Tweets about the Olympic torch, which is wending its way through central London, still poured in, albeit far more slowly than earlier in the day.

When the Olympics open in London today there is expected to be an even bigger spike in use of the micro-blogging site.