An Afghan soldier who opened fire on Australian troops at a remote base last year has claimed he and his fellow army recruits had often discussed killing the foreigners, a report said Saturday.

In a Taliban video, Mohammed Roozi talks about how he attacked Australian and Afghan soldiers at Patrol Base Nasir in November, saying he turned a machine gun and rocket launcher on them before going into hiding.

Roozi, who seriously injured three Australians and two Afghan soldiers in the attack, has been the subject of a manhunt ever since.

"I had one mission on my mind -- to kill foreigners and teach them a lesson. We are Muslims. We cannot accept foreigners," The Sydney Morning Herald cited Roozi as saying in the video.

The former soldier in the Afghan National Army, members of which are being trained by Australian soldiers serving in Afghanistan, said on the day of the attack he prepared the grenade launcher and his gun in front of other soldiers.

"A soldier ran to me and asked me what I was doing," he said. "He suspected my motives. I told him that it was none of his business -- I opened fire. When the bullets ran out it was time to use the rocket launcher."

Roozi also said he was not the only Afghan soldier to harbour murderous thoughts about the western mentors they were working alongside.

"We used to sit there and they were telling these things (attacking foreigners) and whenever it was possible we will do this," Roozi reportedly said.

The Australian military said it had "reason to believe" the man in the propaganda video was Roozi but it said his allegations, which include that he killed 12 Australians, were false.

"Mohammed Roozi is clearly relying on the insurgency for support following his cowardly attack," an Australian Defence Force spokeswoman said.

"His statements are designed to support an ongoing insurgent propaganda campaign and are designed to justify his illegal act."

Australian Prime Minister Julia Gillard dismissed the video as "disgusting" and designed to erode trust between Afghans and Australians troops, some 1,550 of whom are stationed in the strife-torn country.

"The fact that there's this disgusting anti-Australian soldier propaganda anywhere in the world is offensive to me and to all Australians," she said.

Canberra, which has so far lost 32 soldiers in the conflict, has come under pressure over the long-running war in recent months given acts of violence by rogue Afghan soldiers.

Australian soldiers were shot at on three separate occasions by Afghan National Army troops in 2011, with the worst incident being when an Afghan opened fire on a military parade, killing three Australians and wounding seven.

"It's aimed at denting our will," Gillard said of the video. "Well, no amount of propaganda is going to dent our will to get this mission done."