An Australian soldier has been killed and another seriously wounded by an improvised explosive device in Afghanistan, Australian Defense Force confirmed on Saturday.

The member of the First Mentoring Task Force was killed just before midnight (AEST) on Friday, Chief of the Defense Force Air Chief Marshal Angus Houston said on Saturday.

A second Australian soldier was wounded and he remained in a " satisfactory condition".

Air Chief Marshal Houston said the dead soldier had undertaken three tours of Afghanistan in his five years with the army.

The soldiers were part of an Australian patrol conducting operations in the Chora Valley in the Oruzgan province. The incident occurred in an area known as the green zone.

Prime Minister Julia Gillard said the latest loss increased the determination of the soldiers serving in Afghanistan to get the job done.

"There will be Australians today who are asking themselves in the face of this loss why as a country do we continue to pursue our mission there," Gillard told Australian Associated Press.

"We pursue that mission because Afghanistan is a safe haven for terrorists.

"I believe Australia, while mourning these losses, will understand our continuing determination."

Defense Minister John Faulkner said soldiers in Afghanistan were making steady progress in their mission to train the force brigade of the Afghan National Army.

"I have acknowledged progress is not as fast as some would like to see but I still believe there has been a change in momentum in Afghanistan," Senator Faulkner told reporters in Darwin.

Senator Faulkner said he expected that in two to four years the mission would transit to a supporting role.

He noted that in 2010 there had been six Australian deaths and 43 injuries, many of which were not the result of enemy action.

The Australian toll from the almost decade-long war now stands at 17, with 143 soldiers injured.

Six Australian soldiers have now died in Afghanistan in the space of just over a month.