THE personal details of millions of Vodafone customers, including names, home addresses, driver's licence numbers and credit card details, have been available on the web in what is described as an ''unbelievable'' lapse in security by the mobile phone giant.

The Sunday Age is aware of criminal groups paying for the private details of some Vodafone customers to blackmail them.

Other people have apparently obtained logins to check their spouse's communications.

The personal details, accessible from any computer because they are kept on an internet site rather than Vodafone's internal system, include numbers dialled or texted, plus the time and location of calls or texts.

The full extent of the privacy breach is unknown, but The Sunday Age has learnt that possibly thousands of people have logins that can be passed around and used to gain access to the accounts of about 4 million Vodafone clients.