He is the 21st Australian soldier to be killed in Afghanistan and the 10th since June.

ADF chief Air Chief Marshal Angus Houston said the 28-year-old lance corporal was from the Brisbane-based 6 Battalion Royal Australian Regiment.

He was married with children. At his family's request, the soldier's name has not been released.

Air Chief Marshal Houston said the solider was part of a dismounted patrol with Afghan troops through the green zone in a city in the western part of Oruzgan province when their group was fired upon.

"They were engaged by the Taliban and a fairly long firefight ensued and essentially there was a lot of support provided by the Apache helicopter," he said.

"There was also some other support provided, which I won’t mention for operational security reasons, but eventually they made contact and that was that.

"Eventually they broke contact and that was that."

The soldier was given first aid but could not be saved, Air Chief Marshal Houston said.

No other Australian or Afghan soldiers were hurt.

The soldier was described as "very experienced" and popular.

"He was ... a much-loved young man whose death is going to leave a terrible, terrible gap in the lives of those around him," Defence Minister John Faulkner said.

He is the third member of the 6 RAR Battalion to die since Saturday.

Private Grant Kirby, 35, and Private Tomas Dale, 21, were killed and another two soldiers were wounded when an improvised explosive device went off while they were overseeing an Afghan army patrol in the Baluchi Valley.

A further two soldiers were seriously wounded in a separate incident on Saturday.

All six were from the same first mentoring task force involved in today's incident.

SAS Trooper Jason Brown was killed a week earlier in a gun battle in Kandahar province.

The first mentoring task force is involved in mentoring, reconstruction and security operations in the country's southern Oruzgan province.