Microsoft has denied claims that its Xbox Live online gaming network has played host to fraudsters. Neither has Bungie.net, it added.

The software giant's statement follows an investigation into allegations that some Xbox Live users had been locked out of their accounts by third-parties. Some users also reported cases of their credit card numbers being used to buy Microsoft Points, the online service's digital tokens of exchange.

Last night, Microsoft said the service had not been the victim of a security breach. It said it had found "no evidence" of successful attempts to hack into users' accounts.

However, it did warn users to be on their guard from fraudsters who attempt to trick them into handing over information that could be used to subvert their accounts.