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Adobe chief executive Bruce Chizen told Reuters that the company has not received a final copy of Leopard with which to test its software.

"CS3 hasn't fully been tested under Leopard," Chizen said. "If it doesn't work, we will make the necessary adjustments."

Apple has been distributing pre-release Leopard builds to developers since June, when it announced that the release date had been moved back to October. It had originally promised to release Leopard in the spring, but explained that work on the iPhone's OS X operating system and applications had taken precedence.

Chris Swenson, an analyst with market research firm NPD, said that Adobe is trying to buy some time.

"What I think Chizen is saying is that they want more time than what Apple is giving them to make sure everything works," he said. "They just don't want any hiccoughs that could hurt sales."

Apple could not be reached for comment.

Microsoft's Windows Vista operating system, which went on sale at the start of this year, also has had some incompatibility issues with other types of software.