A rocket attack has hit the Taji Military Complex, home to Coalition forces and a combined Australia-NZ military training contingent. It is the second such attack on the complex in the last week.
No Australian soldiers have been injured in either attack.
The first, on March 11, killed three allied soldiers - two Americans and one British - and injured 12. Reports indicate that the first attack involved 18 107mm Katyusha rockets fired from a truck. The US later launched retaliatory strikes against a paramilitary group linked to Iran.
"My heartfelt condolences to the families of those killed in this cowardly attack on the coalition military base in Iraq," UK Foreign Secretary Dominic Raab said. "I spoke with [US Secretary of State] Mike Pompeo last night and we agreed that it is essential to defend against these deplorable acts.
"We must find those responsible. I welcome the Iraqi President’s call for an immediate investigation to hold perpetrators to account - but we must see action."
"Defence condemns these attacks and continues to closely monitor the situation along with our Coalition partners," the Department said in a statement. "The safety of our personnel deployed on operations is our highest priority."