The personal details of thousands of people have been stolen after hackers targeted British games developer Codemasters.
The firm described the data theft as "significant" saying names, addresses, phone numbers and dates of birth were all taken on 3 June.
However, it said that payment details were not compromised.
The latest security breach comes in the midst of a spate of hacker attacks, including several against Sony.
Codemasters said it took the compromised website offline as "as soon as the intrusion was detected".
A subsequent investigation revealed that hackers managed to take the personal details of thousands of users, including names, addresses, email addresses, phone numbers and dates of birth, passwords, IP addresses, XBox gamer tags, and biographies.
In an e-mail sent to some of its customers, the firm advised users to "change any passwords you have associated with other Codemasters accounts.
"If you use the same login information for other sites, you should change that information too.
"Furthermore, be extra cautious of potential scams, via email, phone, or post that ask you for personal or sensitive information."
A spokesperson for Codemasters told BBC News that they still had no idea who targeted their sites, or how many people had their details compromised, although they said that it would affect tens of thousands of users.
Codemasters said its website - codemasters.com - would remain offline "for the foreseeable future" with users being directed to its Facebook page.
Brad Langford from Manchester contacted the BBC after receiving an e-mail from Codemasters, warning that his personal details may have been taken.
He said: "Sensitive information such as date of birth, and some times postal address are tools to hackers who try and steal identities.
"Does a company like Codemasters or any video game company really require such sensitive information? In my opinion - no."
Another Codemasters website user, Leanne Lee from Eastbourne, accused the company of being slow to respond.
"I was a little shocked that it took them a week to let us all know and an impersonal e-mail with no follow up on their Facebook group either except a brief post in their discussion board section.
"We should have been informed as soon as they had taken down the site," she said.