The hacktivists behind a hack on The Sun's website claim to have extracted an email archive which they plan to release later on Tuesday.

News International's systems were hacked on Monday night. As a result, visitors to The Sun's website were redirected towards a fake story on the supposed death of Rupert Murdoch by infamous hacktivist collective LulzSec. The group also redirected visitors to the main News International website to the LulzSec Twitter feed. In addition, the hack may have allowed LulzSec to gain access to News International's email database.

Sabu, a prominent member of LulzSec, said via Twitter that the group was sitting on emails of News International staffers that it planned to release on Tuesday.

In the meantime, Sabu released email login details for former News International chief exec Rebekah Brooks, a central figure in the News of the World voicemail-hacking scandal.

Brooks (then called Wade), edited The Sun between 2003 and 2009, and – at least according to LulzSec – had been using the password 63000 to access her email account at the paper. As IT blogger John Graham-Cumming points out, 63000 is the same number as the text tip-off line used by the Sun.

LulzSec also posted the supposed password hash – but not the password – of Bill Akass, former managing editor of the News of the World.

The hackers also posted the mobile phone numbers of three News International execs. This information seems to have come from, at best, an old database. The Telegraph reports that one of the phone numbers belongs to Pete Picton, a former online editor with The Sun who left to work on News Corp's iPad-only publication, The Daily, last year. Another phone number belongs to Chris Hampartsoumian, an IT worker. Hampartsoumian recently announced, via Twitter, that he does not work for any News Corp firm.

LulzSec certainly obtained deep enough access to News International systems during the Monday break-in to pull off a redirection hack on The Sun, but whether it obtained the depth of access it claims to have done remains unclear. A News International spokeswoman declined to comment when we asked if the organisation was taking the email hack claims seriously or whether it was taking any remedial action.

She said the firm was "aware" of the website redirection hack on The Sun, adding that all News International websites were now up and running as normal.

However The Guardian reports that News International took its webmail systems and remote access systems offline as a precaution following The Sun website redirection hack. Passwords were reset before remote access and other systems were restored on Tuesday morning, the paper adds. ®