The move is supported by Prime Minster Julia Gillard, the country’s first female leader.

“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 front-line combat roles,” Mr. Smith said in the capital, Canberra. “In the future, your role in the defense force will be determined on your ability, not on the basis of your sex.”

Women already play a significant role in the Australian military, which sent more than 2,000 troops to fight in Iraq and currently makes up the largest contingent of any non-NATO member fighting in Afghanistan. As of August, 335 women were serving on overseas operations, accounting for more than 10 percent of Australia’s fighting forces deployed overseas, according to the military.

But while the military says that about 93 percent of positions are open to women under the current policy, many combat roles have remained closed. Under the new plan, which Mr. Smith said had been agreed upon during a cabinet meeting on Monday and which will be carried out over a five-year period, those remaining restrictions will be dropped. Australia will now join Canada, Israel and New Zealand as the only developed countries with no restrictions on women serving in front-line capacities.

Women make up 14 percent of the United States’ armed forces, but they are barred from serving in certain combat roles, including in the infantry and Special Forces, a sore point for many female soldiers who are often attached to combat units in noncombat roles.