Vodafone email customers were left without access this week after a security breach forced the company to suspend the service.

The Vodafone.net site resumed service on Wednesday, having been out of operation for five days.

A Vodafone spokeswoman says the company is carrying out a full diagnosis of the problem.

'We have resolved the problem which was a simultaneous hardware and software failure,' she said.

The company was alerted to the problem by a user who had received emails intended for other subscribers last Wednesday. But it was only when Computing contacted Vodafone on Friday that it took any action.

‘Unfortunately there was a delay in reading the customer’s email, for which we apologise,’ said the spokeswoman.

‘As soon as we were contacted on Friday we did take immediate steps to suspend the service and began an investigation.’

The company has admitted that the web-based service has been closed as a direct result of the security breach, but says it is an isolated incident and will not divulge any further details.

Vodafone mail provides customers with a single mailbox for voice, email and fax messages and is used by a significant number of businesses. Fax and voicemail services are unaffected.