BlackBerry maker Research in Motion has issued a software fix for its mobile email service after flaws were revealed at a hacking conference over the holiday season.

A speaker called 'FX', from the Phenoelit hacking group, revealed the flaws on 30 December at the 22nd annual Chaos Communication Congress in Berlin.

If exploited the flaws could have caused a denial of service attack against BlackBerry handhelds and email servers.

"While 'FX' commended the BlackBerry on its overall security and software coding, it also identified certain potential issues," said RIM in a statement.

"RIM has already developed software fixes for the issues and, although there have been no customer reports of any actual problems, RIM has also provided temporary precautionary measures that can be taken until customers are able to implement the software updates."

The company has applied a software upgrade to its servers and issued an advisory on the problems. The US Computer Emergency Readiness Team has also issued an update on the issue.

BlackBerry users are being urged to upgrade immediately.