Further to the company's official apology for the Gmail outage that left users of the free webmail service without access to their accounts for around 2 hours on Tuesday, Google has updated the community on what went wrong.

Updating a blog post on the topic, Acacio Cruz, the Gmail site reliability manager stated that they were offering the explanation as "lots of folks are asking what happened".

Cruz says: "There was a routine maintenance event in one of our European data centers. This typically causes no disruption because accounts are simply served out of another data center".

"Unexpected side effects of some new code that tries to keep data geographically close to its owner caused another data center in Europe to become overloaded, and that caused cascading problems from one data center to another. It took us about an hour to get it all back under control".

Cruz assures users that the bugs have been "found and fixed".