London, Feb 25: Google has issued an apology to customers after a system crash left millions of users around the world unable to send and receive emails.

Google''s web-based email service, Gmail, got shut for two-and-a-half hours from around 9.30am (UK time), frustrating individuals around the world who rely on the email tool for communication, reports the Daily Express.

According to Internet data company comScore, an estimated 127 million people have Gmail accounts - making it the third most popular email provider after Yahoo and Hotmail.

As technicians worked to fix the problem, the Internet giant apologised to users of the service, stressing that it was an `unusual occurrence'.

Once the problem was resolved, Acacio Cruz, site reliability manager for Gmail, posted a statement on the Google blogspot apologising for the inconvenience.

The statement read: "We know that for many of you this disrupted your working day. We''re really sorry about this and we did do everything to restore access as soon as we could. Our priority was to get you back up and running."

Google also revealed that its engineers were still trying to establish the root cause of the problem.

A representative for Google said: "The problem is now resolved and users have had access restored. We know how important Gmail is to our users, so we take issues like this very seriously, and we apologise for the inconvenience." (ANI)