Women will be allowed to serve in frontline combat roles within five years under changes announced today by Defence Minister Stephen Smith.

Mr Smith said the decision to remove all restrictions on women serving in combat roles was agreed by Cabinet last night and was fully supported by Defence chiefs.

It means women will be eligible to be deployed to combat zones in key roles previously denied to them on the basis of their gender.

"They are mine disposal, divers, Air Force defence guards, and infantry or artillery frontline combat roles," Mr Smith told a news conference in Canberra.

"We have an Australian Army that's been going for 110 years, an Australian Navy that's been going formally for 100 years, and an Australian Air Force that's been going for 90 years, and last night, we resolved to remove the final restrictions on the capacity of women to serve in frontline combat roles."

But female soldiers will have to prove they are physically capable of performing on the same level as their male colleagues.

Defence Science and Personnel Minister Warren Snowdon conceded there would be resistance to the change from some servicemen, saying there were a "variety of opinions" among personnel.

"In some places there will be some resistance which will be stronger than in others," he said.

He said Defence chiefs would have the responsibility to "manage the cultural change" needed to avoid conflict.

"I'm confident that will happen," Mr Snowdon said.

And he said soldiers would be judged on their "physical and psychological capacity to do the work, not on their gender".

Mr Smith said the message to serving women was: "Into the future, your role in the Defence Force will be determined on your ability, not on the basis of your sex."

He said the staged implementation of the policy would ensure military standards were not diminished during the take-up period.

Mr Smith said he knew of a female soldier who was "the best shot in her platoon" but could not serve as a sniper in Afghanistan.

"Why would we take away the chance of the best shot in the platoon from playing that role?" he asked.

"The only thing that would reduce our capability would be by reducing our standards, which we are not proposing to do, or by not allowing the best people to come forward, which is what we are proposing to do."

Mr Smith denied that having women on the frontline in Afghanistan would make Australian troops more of a target for the Taliban.

"This is simply putting into the frontline those people who are best placed to do the job," he said.

The Australian Defence Force has 81,000 full-time personnel and active reservists, of which 14 per cent are women.