One senior police source said intelligence suggested a reason behind the desire to return was because living conditions in Syria are very poor. Khaled Sharrouf, whose family reportedly want to return to Australia. While there is no evidence that Khaled Sharrouf himself wants to come back – a move which would see him face certain prosecution and a lengthy jail sentence – the predicament of his children raises sensitive issues due to their young age. The photo posted on Facebook last year of Sharrouf's seven-year-old boy holding a decapitated head in Syria sent shockwaves around the world. It is understood Sharrouf's three young boys and two teenage daughters are viewed by some senior security sources as victims of their father's extremism. However, the case of Tara Nettleton is more vexed.

She is suspected of helping to spirit her children to Syria via Malaysia after Sharrouf flew out of Sydney in December 2013 using his brother's passport. During this trip, police suspect Ms Nettleton had travelled on return tickets and was accompanied by her mother Karen in order to evade detection by security agencies. Karen reportedly returned to Australia from Malaysia while her daughter and the children flew to the Middle East. The revelations about the possible return of Sharrouf's children bring to the fore the debate about the citizenship rights of those who join IS. On Tuesday, the federal cabinet agreed to introduce laws to strip dual citizens of Australian citizenship if they are suspected of terrorism. A cabinet revolt turned down a proposal to strip sole Australian citizens of their rights. Tara Nettleton's father Peter has previously pleaded publicly for his grandchildren to be returned to Australia, saying he was deeply concerned about their welfare.

Ms Nettleton converted to Islam and had the first of her five children with Sharrouf when she was 17. Mr Sharrouf was convicted and jailed for terrorism offences in Australia, as part of the Pendennis plot, but was released before joining ISIS. He has posted shocking pictures on social media, including those showing his children, while fighting with the terrorist group. Last Week, Fairfax Media interviewed Australian nurse Adam Brookman, who claimed he was forced to join ISIS after flying to Syria last year to perform humanitarian work. Mr Brookman also claimed he managed to escape the group and, in comments viewed sceptically by senior police, that he abhorred ISIS's operations.

The federal police initially blocked efforts by Mr Brookman's lawyers to attempt to facilitate his return to Melbourne. It is understood that police have since agreed to speak to his lawyers.