THE government has finally backed down on its plan for a controversial mandatory internet filter, and will instead rely on major service providers to block ''the worst of the worst'' child abuse sites.

The retreat on the filter, which Labor proposed from early in its term, comes after a strong campaign by providers. Opponents argued it would not be effective, would be costly and slow down services, and involved too much censorship.

Communications Minister Stephen Conroy, who strongly argued the case for years, will announce on Friday that providers blocking the Interpol worst of the worst list ''will help keep children safe from abuse''.

''It meets community expectations, and fulfils the government's commitment to preventing Australian internet users from accessing child-abuse material online.''