Blackmail demands followed the theft of personal details – including home addresses and phone numbers – from Monster.com

Personal details stored on Monster.com, a website that lists job vacancies, were taken after a raid by hackers who posed as employers to gain access to the site. Having stolen the information, hackers e-mailed the victims claiming to have infected their computers with a virus and threatening to delete files unless demands for payment were met.

The details, which included names, surnames, e-mail and home addresses, as well as phone numbers, were then used to send 'phishing' e-mails to members, apparently from Monster.com, encouraging them to download a tool known as 'Monster Job Seeker'.

A statement from the company said that it would "take all necessary steps to mitigate the issue, including terminating any account used for illegitimate purposes".

Last year, a British woman was blackmailed after hackers used a trojan to gain access to her personal e-mails.