Senior officers say Australia has recently deployed troops with diagnosed mental illnesses and on multiple tours of duty, but not because of any shortage of elite combat troops.

Vice Adm. Ray Griggs, who is acting chief of defense, told a Senate committee on Wednesday that he did not know if any of the 200 commandos and Special Air Service troops who will soon deploy from the United Arab Emirates into Iraq to advise and assist Iraqi security forces in their fight against Islamic State militants was taking anti-psychotic medicine.

But he says Australia does deploy troops "with antidepressants."

Rear Adm. Robyn Walker, who heads the defense health section, said seven personnel on "mental health-related medications" have been deployed on overseas operations since 2012.