The Australian Greens say the government's internet censorship trial won't be effective as any customer can choose to opt in or out.

"I'm puzzled the government has chosen to conduct an optional trial of its mandatory internet filter," said the Greens Communications Spokesperson Senator Scott Ludlam.

"Those who download illegal material are hardly going to sign up to the trial. What can the government hope to achieve when the plan's target group won't even participate? It's like trialling tough new laws against fraud, but letting the fraudsters opt out."

"At this stage, only a few ISP providers have chosen to participate in this trial, which means few internet users are going to be involved. It's impossible to draw any conclusions from a trial involving such a small sample size."

"I can only assume that this trial is for show, so the government can tick a box and say they've tested this deeply unpopular censorship plan before implementing it."

"The Minister says he's aware of technical concerns regarding the internet filter, yet he's again stayed silent on the much larger issues of government control of information, and freedom of expression," concluded Senator Ludlam.

For more information or media enquiries please call Robert Simms on 0417 174 302