BT has apologised for losing emails belonging to 3,500 customers.

The cock-up took place last week and wiped out emails belonging to users of BT's Web-based talk21 email service. The glitch happened during maintenance of 3,500 email accounts.

As a result users were unable to access their email for several days. And incoming email was also rejected while the service was down. BT has confirmed that it is unable to retrieve these emails.

In some cases BT has also lost emails that had already been received. It says it is working to restore these emails as soon as possible.

In an email to those hit by the glitch BT said: "Last week, there was a technical problem that affected a small number of our customers. We are extremely sorry for any inconvenience and have taken steps to ensure it does not happen again."

Talk21 has almost one million active accounts. ®