A $25,000 Mac virus-writing competition has been cancelled - because Apple is worried about the real possibility of people creating one.

The contest, run by DVForge, was intended to undermine recent suggestions by Symantec that threats against OS X were on the rise. But Apple security experts warned that such a virus was possible, and a lawyer warned that encouraging its creation could be regarded as illegal, prompting the company to pull the competition.

Jack Campbell, CEO of DVForge, said the contest was intended to counter what he called fear-mongering by anti-virus companies. The Symantec warnings were baseless and intended only to "scare the hell out of people," Campbell said. Company employees, including Campbell, "lost our minds" when they read about Symantec's claims, and saw the report as a threat to DVForge's business, as much as Apple's.

The idea of a contest grew out of conversations with technical staff at DVForge and was intended to call Symantec's "bluff," Campbell said."We have just as much incentive as Apple to fight back," he said.

The company placed two G5 PowerMac computers running OS X 10.3 Panther on the Internet and issued a statement on its website that challenged Internet users to create a virus that would spread between the two machines on or before 31 July. In a dig at Symantec, DVForge offered double the reward, $50,000, to any employee of Symantec who won the contest.

Campbell was confident that the security features in OS X would prevent anyone from creating a self-propagating virus that moved between the two machines before the deadline expired, he said.

However, after word of the contest quickly spread online, Campbell was contacted by senior Apple employees who were experts on OS X security. They said that it was possible to create such a virus, though doing so would be difficult. The Apple employees encouraged Campbell to end the contest. He was also contacted by an intellectual property attorney and Mac enthusiast, who warned him that writing a virus could be considered illegal, and that DVForge could be considered to be aiding and abetting an illegal activity by sponsoring the contest.

Worried about the prospect of embroiling his company in a legal battle, Campbell cancelled the contest. However, he also issued a strongly worded statement on the DVForge website that railed against Symantec and "the rest of the fear-breeding folks who (prey) on the lack of knowledge about how viruses work."

Some things never change. Will Mac users never recognise that their operating system is just code like everyone else's?