The Australian government will compel internet service providers (ISPs) to block Interpol's "worst of the worst" child abuse websites under existing legislation and dump its controversial plans to implement a broader mandatory internet filtering scheme.

Almost three years since originally announcing the formal scheme , and five years since the idea of a filter was first floated, Communications Minister Stephen Conroy said today that the federal government will no longer seek to introduce a mandatory internet filtering scheme for websites that the Classifications Board calls "refused classification," being beyond X rated.

Instead, the government has issued notices to Australian ISPs, and will compel them to implement the Interpol internet filter under obligations set out in Section 313 of the Telecommunications Act. Telstra, Optus and CyberOne have already implemented the filter; however, major telecommunications company iiNet and its subsidiary Internode were strongly against the voluntary filter and refused to sign up unless the government forced them.

Conroy said that forcing ISPs to implement the Interpol filter removes the need for mandatory internet filtering legislation.

"Blocking the Interpol 'worst of' 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," Conroy said.

"Given this successful outcome, the government has no need to proceed with mandatory filtering legislation."

The Australian Federal Police (AFP) will now issue notices to the smaller ISPs to implement a similar regime.

Conroy said that with the support of major ISPs and the Internet Industry Association (IIA), 90 percent of the Australian population will be covered by the filter. He said that the existing implementation with the likes of Telstra and Optus had shown no impact on internet speeds.

"Several Australian ISPs have already been blocking sites on the Interpol list for over a year. They are reporting that this has had no impact on internet speeds or congestion, and they have had no reports of people being denied access to legitimate web content."

Accompanying Conroy's announcement, IIA CEO Peter Lee said that the move is a "positive step forward."

In the first three months of the operation of Telstra's Interpol filter, the AFP revealed that Telstra had blocked 84,000 attempts to access sites on the list, but documents obtained under Freedom of Information (FOI) revealed that 52,000 of these requests came in the first month, with a significant drop-off in the following two months.

iiNet's chief regulatory officer Steve Dalby confirmed to ZDNet that iiNet had been in discussions with the government on the voluntary filter, and said that the company would comply with the direction to block websites deemed illegal by the government.

By using existing legislation, the government has side stepped attempting to introduce mandatory internet filtering legislation in the parliament. The legislation would have been unlikely to pass in this parliament, because both the Greens and the Coalition were against the mandatory internet filter.

The controversial mandatory internet filtering plan had long been deemed "dead, buried, and cremated" as a result. Legislation was due to be implemented in mid-2013 after the government acted on recommendations from the Classification Review, which recommended a tighter definition of what is defined as "refused classification" eight months ago.

Yesterday, the Australian Christian Lobby called for a mandatory internet filter for all pornography .

Australian Christian Lobby national director Jim Wallace today indicated that the group believed that the government had backed away from an election promise.

"Although child abuse material is the most heinous element of the Refused Classification category, it is just a part of the prohibited online content the government committed to blocking at the ISP level prior to the last election,” Wallace said.

"Having ISPs block only illegal child abuse material does not meet the government's cyber safety election commitment to mandatory ISP filtering of Refused Classification material. The government's decision not to legislate to the full extent of its commitment is a great disappointment."