In one of the biggest cases of data theft, hackers have stolen the personal data of millions of job hunters from Monster.co.uk.
The information, that includes user names, passwords, telephone numbers and email addresses, could have been stolen from as many as 4.5 million users of the job seeking site.
The site says: "Monster is the target of illegal attempts to access and extract information from its database. We recently learned our database was illegally accessed and certain contact and account data were taken, including Monster user IDs and passwords, email addresses, names, phone numbers, and some basic demographic data".
Although the information is not said to include personal financial data, the theft could put many who use the same user names and passwords on other sites at risk.
Monster.co.uk has issued a statement saying it has warned its users, launched an investigation and has now taken "corrective steps".