Google has apologised after its Gmail email service went down for a number of hours on Tuesday.

Although the Search Engine has failed to give a reason, as yet, to what caused thousands of Gmail users to be without the free beta service it has said the problem is now fixed.

"Many of our users had difficulty accessing Gmail today. The problem is now resolved and users have had access restored". Google said on its support pages. "We know how important Gmail is to our users, so we take issues like this very seriously, and we apologize for the inconvenience".

The service went down at around 9:30am GMT with users unable to access the website to access mail, although they could access it via their desktop inboxes and phones.

"It's a worry", one company who uses the service for its corporate email told Pocket-lint at the time "If I can't trust it, I will have to move to another offering".

Recently high-profile companies, such as UK newspaper The Guardian, moved to the free service in an attempt to save money.

This is the second hiccup by Google in as many months, in January human error forced Google to believe every site on the Internet was malware.

UPDATE: Google has now posted a statement on its blog, however still not explained what caused the issue:

"The Gmail outage that affected many consumers and Google Apps users worldwide is now over. Users should find that they’re able to access their email now without any further problems.

Before you can access your Gmail, you may be asked to fill in what’s called a ‘CAPTCHA’ which asks you to type in a word or some letters before you can proceed. This is perfectly normal when you repeatedly request access to your email account, so please do go through the extra step – it’s just to verify you are who you say you are.

The outage itself lasted approximately two and a half hours from 9.30am GMT. 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. Our engineers are still investigating the root cause of the problem.

Obviously we’re never happy when outages occur, but we would like to stress that this is an unusual occurrence. We know how important Gmail is to you, and how much people rely on the service.

Thanks again for bearing with us.

Posted by Acacio Cruz, Gmail Site Reliability Manager"