SAN FANSCISCO, USA: A disruption to Google's Gmail service frustrated users throughout the world Tuesday and flummoxed engineers at the giant internet company.

Google said the problems started early in the morning and were not resolved until approximately 2330 GMT.

The problem prevented users from accessing Google email and stymied customers who use the popular software to sync their information with the Microsoft Outlook email programme.

In Google's Gmail forum, users claiming to be in Italy, Germany, France and Taiwan, along with users from various states in the US, reported being unable to access Gmail.

The snafu increased concerns about the safety and integrity of online data as more computer users migrate to using popular internet services offered by the likes of Google, Facebook and Microsoft.

Google is the third-most popular online email service in the US after Yahoo and Microsoft's Hotmail. The service suffered outages in February and previously in April, August and October 2008.