More Aussies killed fighting for ISIS

Up to eight more Australians have reportedly been killed fighting for Islamic State in Iraq and Syria since June.

Around one third of Australian fighters who have joined the conflict in Iraq and Syria have reportedly been killed.

Foreign Minister Julie Bishop told The Australian that at least 40, and possibly as many as 43, are believed to have died fighting for Islamic State - up from the estimated 35 in June.

"The number of foreign terrorist fighters joining the conflict in Syria and Iraq continues to grow," Ms Bishop said.