An Australian soldier serving with Mentoring Task Force 3 has been killed in action in Afghanistan.

The soldier, from the Townsville-based 2nd Battalion RAR, was seriously wounded by what is thought to be an IED blast while on a night patrol with the Afghan National Army in the Khas Uruzgan region, 85 kilometres north-east of Tarin Kot.

He was given immediate first aid and evacuated to the medical centre at Tarin Kot, but died from his wounds shortly after arriving after 2.30am (local time) on Monday.

No other Australian soldiers were wounded in the incident, but another ISAF soldier was seriously wounded and was in a stable condition.

Chief of Defence General David Hurley offered his condolences to the soldier's family and said they had asked for his name not to be released at this time.

"They face difficult times ahead, but we will take care of them, they will not face these difficulties alone," he said.

General Hurley said the soldier's colleagues described him as a man who "excelled at any task" and was "proud to serve his country".

"In the coming days the members of Mentoring Task Force 3 will prepare to send him home," he said.

"I am confident the members of Mentoring Task Force 3 will honour his memory and continue their mission."

He said the soldier had been in Afghanistan since June on his first deployment after having previously served in East Timor in 2009.

General Hurley said an investigation into the incident was underway.

Eight Australian soldiers have been killed in Afghanistan this year and 29 have been killed since the start of the war in 2001.

Prime Minister Julia Gillard offered the nation's condolences to the dead soldier's family and colleagues "as they absorb the most dreadful of news".

"This fighting season in Afghanistan has been a very hard one for our nation, we grieve for too many young lives lost," she said.

"As I've said before I can't promise the Australian people there won't be other days like this, but what I can promise is that we are making progress [in Afghanistan].

"We remain determined to see this mission through. We remain determined that Afghanistan does not become a haven for terrorists."

Defence Minister Stephen Smith also offered his condolences to the dead soldier's family, friends and mates.

"This will be a terrible blow to an Australian family tonight," Mr Smith said.

"This will also be a terrible reminder to the 28 other Australian families. The thoughts of the entire nation will be with those families.

"So far as our mission in Afghanistan goes, I believe we are on track to achieve our mission.

"This of course does not make it any easier for the nation or any family to bear the burden of another fatality, but we believe what we are doing in Afghanistan is in the national interest."