Five Australian soldiers killed in Afghanistan

Five Australian soldiers were killed in two separate incidents in the past 24 hours in Afghanistan -- including three in an "insider attack" -- marking the country's highest combat toll since the Vietnam War.

Chief of Defence Force Air Marshal Mark Binskin said two Australian soldiers had been killed in a US Black Hawk crash in Afghanistan on Thursday.

Earlier, three Australian soldiers were killed and two injured in an attack in Afghanistan by a man wearing an Afghan army uniform, calling it a "green on blue" attack.

The ISAF has gathered some information about the perpetrator of the insider attack, who attacked the soldiers while they were relaxing at the end of the day.

"We are currently trying to track him as he has escaped. But I don't want to get into any more details on him at this moment," Binskin said.

Calling the incident "truly shocking", Prime Minister Julia Gillard said, "I believe this is the most losses in combat since the days of the Vietnam War and the battle of Long Tan."

"We are making progress. I can tell you that, I have seen with my own eyes when I have visited Afghanistan," Gillard told reporters.

The shooting happened 20 km north of Tarin Kowt, where the soldiers were fired on at close range in a cross-fire. The motive behind the attack is yet to be ascertained.

Nearly 1,550 ADF troops are deployed in Afghanistan as part of the International Security Assistance Force. It has lost 33 soldiers in Afghanistan since February 2002 till today.

According to ISAF, this year, more than 30 insider attacks have killed 45 coalition troops, making up about 14 per cent of the overall death toll in the war for 2012.

Most foreign combat troops are due to leave Afghanistan by the end of 2014, handing security responsibility to their Afghan counterparts.

However, Gillard has ruled out any plans of early exit.