"The government's policy was broader in scope than just focusing on child abuse images and the breadth of scope was something that was of concern for us at Yahoo!7," she said.

"We also felt imposing a filter through legislation might have been a bit pre-emptive in terms of trying to seek a collaborative process with industry more broadly before taking that step."

Microsoft Australia chief security advisor, Stuart Strathdee, said the reliance on a single method of protection was problematic.

"I'd highlight the difficulties in selecting a single technology to try to implement that style of protection," he said.

"I think this issue is a challenging one and we need to look more broadly at a combination of technologies and education to combat it. One technology isn't going to be the solution.