In television shows, on Facebook and on Twitter, Musa Cerantonio urged Muslims to take up arms and use violence.

He was a leading propagandist for theIslamic State in Iraq and Syria ( ISIS ). One in four foreign fighters in Syria followed his Twitter account, according to The Australian newspaper.

But Cerantonio – a former Catholic from Australia– was not always truthful about who he is and where he was.

In July, he boasted on Twitter of having made it to the Middle East. But authorities arrested him that same month on the resort island of Cebu in the Philippines, where he had been living for a year.

The Filipina woman with whom he was living at the time of his arrest, said despite his violent rhetoric, Cerantonio couldn't "even kill an ant", Australian paper The Age, reported.

Be sceptical about social media

As radicals use social media to recruit young Muslims to wage jihad in conflict zones, a surprisingly high number of active social media-using jihadists are actually Westerners, according to a study by London-based think-tank International Centre for the Study of Radicalisation and Political Violence (ICSR).

An ICSR research team spent a year compiling a database of social media profiles of 190 Westerners believed to be fighting in Syria .

Religious activists and leaders urge young people in particular not to be swayed by jihadist recruitment propaganda disseminated via Twitter, Facebook and YouTube.

The most notable instance was the YouTube video posted last month that featured a wanted Indonesian terrorist calling for Indonesian Muslims to join ISIS in the Middle East.

"We need to always be critical, analytical and sceptical when we come across such information on social media," said Beni Pramula, chairman of the Muhammadiyah Student Association (IMM) and a postgraduate student at Mercu Buana University in West Jakarta. "Be selective when absorbing that kind of information, and it is better to discuss with friends or ustadz to get a better perspective.

" If it's bogus , what we can do is to stop that information ourselves and not disseminate it further," he added.

Nahdlatul Ulama scholar Masdar Mas'udi said Islamic ulemas and teachers should increase their efforts to help young Muslims properly interpret information they receive online.

"It takes a certain level of intelligence to digest such information, therefore, it should be up to the people that these youngsters look up to, such as their teachers, to tell them not to easily believe in such propaganda," Masdar told Khabar.