Mac users who've chosen to avoid the £54 price tag for Apple's newly announced iWork 09 software suite could get a nasty surprise.

Intego, a company that specialises in security software for the Mac, has discovered a Trojan horse, the OSX.Trojan.iServices.A. It is currently circulating in copies of Apple’s iWork 09 found on BitTorrent trackers and other sites containing links to pirated software.

Although the pirated versions of the software are complete and fully functional, the download actually comes with an additional package that once installed gives a hacker access to all areas of the computer remotely via the Internet.

That hacker is then free to install other applications, possibly causing users further issues.

Although not specifically a virus, as you can only get it via actively downloading it, the news is likely to send shockwaves of panic through the Mac community who have always felt that they are immune from virus or Trojan threats.

Intego, either looking to push its software that will of course save you from the infection or just do the right thing, says that it raised the alert "to warn Mac users not to download iWork 09 installers from sites offering pirated software".

The company cites that "at least 20,000 people have [already] downloaded this installer" with the caution that "users may face extremely serious consequences if their Macs are accessible to malicious users".