An Australian teenager, who told his mother he was leaving on a fishing trip earlier this year, has emerged in a chilling Islamic State video, warning Prime Minister Tony Abbott and the west that the terror group cannot be stopped.

The speaker, believed to be 17-year-old Abdullah Elmir, who is also known as the 'Ginger Jihadist', threatens revenge against western leaders, and directs a specific threat to Tony Abbott and Australia, over airstrikes on Islamic State militants in Syria and Iraq.

It is believed to be the first time the Islamic State has mentioned Mr Abbott and Australia in one of its propaganda videos.

In the two-minute clip posted online on Monday night, the teenager, who is dressed in military attire, holding a rifle and flanked by fellow jihadists, warns: "This message I deliver to you, the people of America. This message I deliver to you, the people of Britain, and I deliver this message to you, especially, the people of Australia.

"Bring every nation that you want to come and fight us. It means nothing to us. Whether it's 50 nations or 50,000 nations, it means nothing to us. Bring your planes. Bring everything you want to us. Because it will not harm us. Why? Because we have Allah."

He goes on: "To the leaders, to Obama, to Tony Abbott I say this; these weapons that we have, these soldiers...we will not stop fighting. We will not put down our weapons until we reach your lands, until we take the head of every tyrant and until the black flag is flying high in every single land."

Sydney teenager, Abdullah Elmir, has surfaced in a chilling Islamic State video threatening Prime Minister Tony Abbott and other western leaders over air strikes in Iraq and Syria. Photo: ABC More

He vowed the group will not stop fighting until it has conquered the west and the black flag is flying above the White House and Buckingham Palace.

Elmir vanished from his family's Bankstown home in June after telling his parents he was going fishing.

News break - October 21