Crossbench MPs have spoken out in Parliament against Australia's commitment to the Afghanistan war, calling for troops to be brought home immediately.

Debate on the conflict began in Parliament yesterday with Prime Minister Julia Gillard and Opposition Leader Tony Abbott voicing their bipartisan support for continued involvement in the war-torn country.

But Greens MP Adam Bandt and independent MP Andrew Wilkie have slammed Australia's continued troop deployment as unjustifiable, dangerous and wrong.

Mr Bandt says efforts to train local forces have not been as successful as the Government says.

"I know many Australians ask the legitimate question: what will happen to the population if we pull out? But there's an alternative question - is us being there making the problem worse?" he said.

Mr Bandt will introduce a bill which would require future deployments to be approved by both houses of Parliament.

Ms Gillard warned yesterday that Australia will be involved in Afghanistan for at least the rest of this decade but Mr Bandt said this was not acceptable.

"If coalition troops are there for another decade, a whole generation of boys and girls will have grown up under occupation and we must expect all the consequences that may flow from that," he said.

Mr Wilkie, a former military officer and intelligence analyst, described Ms Gillard's statement as "extraordinary".

"If it was up to me, I'd be very concerned with any military plan that still had us fighting in Afghanistan in 10 month's time, let alone 10 years," he said.

Mr Bandt said the Government had not adequately addressed allegations of corruption and criminality in Afghanistan's Karzai administration.

"On Monday I asked a question of the Minister for Defence about the alleged criminality of the Karzai government. He dodged the point and again yesterday, and today the Government has failed to respond directly," he said.

Mr Wilkie took aim at the Government and Opposition's argument that Australia needed to stay on in Afghanistan to stop terrorism threats.

"Ditch the dishonest terrorism rhetoric and try and sell the real reasons for our seemingly open-ended involvement in a war that has gone from bad to worse over nine years, making it one of the longest wars in Australian history." he said.

Mr Wilkie says while he is pro-United States, Australia would be at less risk of being taken for granted if it sometimes said no.

And he questioned why other MPs were not speaking out.

"Whatever happened to some of you that now you're so ready to sacrifice your soul for your party's political self-interest?" he said.

Defence Minister Stephen Smith, who also spoke in the Parliament today, said progress was being made and it was essential for Australia to remain in Afghanistan.

"The international community has cause for cautious optimism but we face a resilient insurgency and the situation in Afghanistan remains difficult, serious and dangerous with the potential to revert," he said.

Opposition defence science technology and personnel spokesman Stuart Robert says Australia must support the United States or risk being exposed to regional threats.

"This will require a strong and credible US as a counter balance, not one damaged from defeat in Afghanistan," he said.

"Our regional security remains predicated on the US's capacity to take decisive military action if required.

"A failing and weak Pakistan would be a significant problem for India and thus a significant regional issue."