TWO brothers aged 15 and 16 suspected of trying to leave Australia to fight in the Middle East were detained at Sydney Airport by counter-terrorism officials before being taken home by their mum.

Amid fears that Islamic State is recruiting Aussie teenagers as “cannon fodder’’, authorities are confident they have saved the two Sydney teens from a potentially deadly adventure.

Tony Abbott urged young Australians being lured by the terror group to “block your ears” following the revelations concerning the teens.

media_camera CCTV vision of the two teenage brothers (centre of pictur) suspected of trying to fly to the Middle East to fight. (AAP Image/ Sydney Airport)

media_camera Customs officials and a member of the counter-terrorism unit check the belongings of the brothers. Picture: AAP Image/ Sydney Airport.

The Prime Minister said the arrests showed the Coalition’s tough border protection laws were working.

“These were two misguided young Australians ... who had succumb to the lure of the death cult,” Mr Abbott said.

“I’m pleased that they have been stopped and my message to anyone who is listening to the death cult is block your ears.

“Block your ears. Don’t even begin to think that you can leave. We will stop you at the border on the way out and if you get out we will stop you at the border on the way back.”

media_camera Cracking down ... Prime Minister Tony Abbott has sent a strong message to anyone planning to join Islamic State from Australia.

Immigration and Border Protection Minister Peter Dutton revealed two teenagers were stopped on Friday night.

They had booked return tickets to an undisclosed location in the Middle East. But authorities will allege that fears were raised over their travel plans after their bags were searched.

After being detained at the airport for several hours they were allowed to return home with their parents.

Mr Dutton said the boys had aroused the suspicion of “two alert Customs and Border Protection officers” who referred them to the terrorism unit.

“What we have here are two teenagers who have been intercepted on their way to a potentially very dangerous situation,” Mr Dutton said.

“As a result of this interception, a Sydney family remains together.

media_camera Border Protection Minister Peter Dutton wants parents to remain vigilant.

“This highlights afresh the need to work within communities and with parents to disrupt attempts to brainwash our young people.

“It is yet another reminder of the need for parents to remain vigilant against this type of threat.

“This event also showcases the critical work of Australian Customs and Border Protection officers operating around the clock at our borders to prevent people travelling in this way.”

Mr Dutton said the spate of recent cases underlined the need for parliament to pass new laws to establish a new Australian border force to collect biometric data at airport and sea ports.

Last June, Sydney teenager Abdullah Elmir, 17, fled Australia with a 16-year-old friend. Elmir later resurfaced in an Islamic State propaganda video warning he would fight until the Islamic State flag was flying at Buckingham Palace and the White House.

In the video he said: “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.’’

But his 16-year-old friend was rescued by his father and returned to Australia and high school.

More than 100 Australians are now estimated to have travelled overseas to fight in Iraq and Syria.

media_camera Australia treasurer Joe Hockey has thanked customs officials for their work. Pic Peter Wallis

They include 22-year-old Gold Coast woman Amira Karroum, who was murdered within days of arriving in Syria last year.

Treasurer Joe Hockey also thanked the customs officials for doing a “great job”.

He said this new terrorist threat is being supported by the “poison” that is coming through the internet and through the words of others.

“It is hammering the brain of young Australians,” Mr Hockey told Sky News.

He said the government’s changes to metadata laws are aimed at stopping terrorism affecting the brains of everyday young Australians.

“If we can stop the poison we can stop young Australians from doing stupid things like trying to go over and fight in the armageddon of war in the middle east,” Mr Hockey said

Last month Foreign Minister Julie Bishop said up to 40 Australian women were also known to have travelled to Syria and Iraq to become “jihadi brides” or work with terrorists.

“More women are either joining their foreign fighter husbands or apparently seeking to find partners, the so-called jihadi brides, or are otherwise providing support for terrorist organisations,” Ms Bishop told parliament.

Under new laws recently passed by parliament, known as the Foreign Fighters Act, customs officers are allowed to detain people where the officer has reasonable grounds to suspect that the person is intending to commit a Commonwealth offence or is a threat to national security or the security of a foreign country.