Three Australian soldiers were killed in southern Afghanistan yesterday by a gunman wearing an Afghan army uniform and two were killed in a helicopter crash.
It is the latest in an alarming series of "rogue" shootings that have damaged trust between the Afghan government and its allies.
The Australian Defence Force confirmed the nationality of the soldiers who were serving in southern Uruzgan province, where around 1,500 Australian troops are based.
It said families in Australia were being informed of the deaths.
The deaths bring to 15 the number of foreign soldiers killed this month in insider attacks.
NATO-led forces have increased security to try to prevent them, including requiring soldiers to carry loaded weapons at all times on bases.
US Joint Chiefs of Staff chairman Martin Dempsey visited Kabul last week to discuss the worrying increase in rogue shootings.
US President Barack Obama also expressed his "deep concern" over the insider attacks.
Mr Dempsey urged Afghan officials to take tougher preventative action, although Western commanders have ruled out cutting back training and support between NATO-led troops and their Afghan allies.
The killings, many of which have been claimed by the Taliban as evidence of their ability to infiltrate Afghan security forces, are particularly worrying as security transition plans gather pace.
Under those plans, all foreign combat troops are due to leave Afghanistan by the end of 2014.
The alarming rise in rogue shootings has raised more questions about the readiness of Afghan forces to take over.
Including yesterday’s shooting, there have been 34 insider attacks this year, leading to 45 coalition deaths, the majority of them Americans.
They account for 14% of all deaths suffered by the NATO-led coalition in Afghanistan this year.
That is a sharp increase from 2011, when 35 coalition troops were killed in such attacks, 24 of them Americans.
Afghanistan's government said last week it would re-examine the files of 350,000 soldiers and police to help curb rogue shootings of NATO personnel. But, in a swipe at neighbouring Pakistan and Iran, it also accused "foreign spies" of instigating the attacks.
Australian Prime Minister Julia Gillard said she would cut short her visit and return to Australia later today for briefings on the deaths.
Opinion polls in Australia say Australians overwhelmingly want their troops out of Afghanistan, although Gillard ruled out any early exit.
