UPDATE: Microsoft has told Eurogamer that it's aware of a few incidents of "unauthorised access" and is working with the relevant individuals to remedy the situation.
However, the spokesperson insisted there is no evidence of a wider Xbox Live security issue. Here is its statement in full:
"We do not have any evidence the Xbox Live service has been compromised. We take the security of our service seriously and work on an ongoing basis to improve it against evolving threats.
"However, a limited number of members have contacted us regarding unauthorised access to their accounts by outside individuals. We are working with our impacted members directly to resolve any unauthorised changes to their accounts.
"As always, we highly recommend our members follow the Xbox LIVE Account Security guidance provided at www.xbox.com/security to protect your account."
ORIGINAL STORY:A number of Xbox 360 owners have reported their accounts compromised and credit cards used to buy FIFA-related content.
Reports suggest FIFA Ultimate Team content packs are the target for those who have gained access to accounts.
Eurogamer was first alerted to the issue by reader Speedjack, who on 11th October found his gamertag had been "recovered" to someone else's machine.
"I then find out that I've had 5000 then 500 MS points bought on my credit card. Better yet, all the points including the 120 I had already on my account are gone... all spent on FIFA 12 content packs yesterday afternoon while I was at work.
"Not only that, but my account now has 35 FIFA 12 achievement points on it!!! Never played the game in my life - hate football."
Speedjack spoke to Microsoft support, which suggested there exists an issue with EA's servers that leaves XBL accounts vulnerable.
It is important to note that at this stage there is no evidence to support this claim, and it is unclear exactly how widespread the issue is.
However, Speedjack is not alone in having his XBL account compromised and used to buy FIFA-related items.
A detailed report on the Goosterblog recounts how one user suffered an XBL account hack - also used to buy FIFA Ultimate Team packs.
The report offers a number of explanations, including one specific to FIFA that involves hackers emailing EA support and the EA server then sending over the victim's Xbox and EA account information.
Microsoft support is freezing accounts affected for up to 30 days as it investigates complaints.
EA was unable to comment on the situation when contacted by Eurogamer, but the company did point our readers towards the EA forum, which offers advise on how to protect user accounts.
It contains information on fake emails and copycat websites, phishing, redirects, scare tactics and password integrity.