The Oak Ridge National Laboratory (ORNL) in Tennessee has warned some 12,000 people that their personal data may have been stolen as part of a ?sophisticated cyber attack?.

Hackers sent lab employees e-mails that seemed legitimate but contained attachments that, when opened, gave the hackers access to their computers. The 'phishing' scheme apparently allowed the hackers to download personal information about people visiting the laboratory between 1990 and 2004.