Google has criticised the Australian government's forthcoming mandatory ISP censorship system for targeting a "too wide" a range of content.

While supporting blocking of child abuse material, Iarla Flynn, Google Australia's head of policy today wrote that "moving to a mandatory ISP filtering regime with a scope that goes well beyond such material is heavy handed and can raise genuine questions about restrictions on access to information".

Google said its intervention was motivated by its "bias in favour of people's right to free expression".

The Australian government yesterday announced laws to impose the filters, following trials.

As well as child abuse material, the Australian filters will block "bestiality, sexual violence, detailed instruction in crime, violence or drug use and/or material that advocates the doing of a terrorist act". The blacklist will be drawn up by the Australian Communications and Media Authority, which also regulates broadcasters.

Citing instructions for safer drug use and sites about euthansia as examples of content that may be blocked, Flynn wrote: "This type of content may be unpleasant and unpalatable but we believe that government should not have the right to block information which can inform debate of controversial issues."

Google's influential voice adds to opposition to the laws, which has united civil libertarians, ISPs and the Australian Sex Party.

Commmunications minister Stephen Conroy, who has driven the filtering scheme, has so far dismissed concerns however. He is backed by Christain groups.

Conroy said popular comparisons with China's Great Firewall, which is used to suppress dissent online, are "baseless". Google's principled criticism makes no such comparison, despite the fact that China is a massive emerging market for its search engine. ®