The Islamic State (IS) Sunni extremist group has urged its cadres to attack civilians of the West, including Australia, media reported Monday.
IS spokesman Muhammad al-Adnani, made the call in an online post, the Canberra Times online reported.
It is the IS's first blanket call for violence against countries planning military action in Iraq.
In his statement, al-Adnani has mentioned Australia three times amid page after page of apocalyptic threats against "crusaders".
"If you can kill a disbelieving American or European -- especially the spiteful and filthy French -- or an Australian, or a Canadian, or any other disbeliever from the disbelievers waging war, including the citizens of the countries that entered into a coalition against the IS, then rely upon Allah, and kill him in any manner or way however it may be," al-Adnani quoted as saying.
"Do not ask for anyone's advice and do not seek anyone's verdict. Kill the disbeliever, whether he is civilian or military, for they have the same ruling. Both of them are disbelievers."
In an over 11-page statement, he urged followers to go for martyrdom, telling them they are "like predatory warriors" who "face death with bare chests".
This threat comes after anti-terror raids were carried out in Sydney and Brisbane last week.
World leaders are also set to discuss how to combat the problem of foreign fighters travelling to Iraq and Syria at the ongoing 69th UN General Assembly session in New York.
Al-Adnani is regarded as the most authoritative spokesman at IS, earlier known as the Islamic State of Iraq and Greater Syria (ISIS). The statement represents the most concrete threat yet to Australia by the group's leadership.
"The Australian government is considering the statement by the IS to be authentic," said a spokeswoman for Prime Minister Tony Abbott Monday.