A group of 34 Australian women and children who have been held in a camp in northern Syria for nearly seven years due to their links to the Islamic State (IS) group were released on Monday to head home, but then returned to the camp for "technical reasons".

The group - thought by authorities to be the wives and children of IS fighters - have been stuck in Roj detention camp until now, with the Australian government refusing to officially repatriate them.

It is unclear why their release was halted, but Australian media has reported it may have been due to a failure to coordinate the correct permissions between the factions governing the region.

Their future - and that of thousands of other IS relatives in Syria - remains unclear. Other foreign governments have also refused to repatriate their citizens.

Reuters news agency quoted a co-director of Roj camp as saying that the 34 Australians had been handed over to members of their families who had travelled to Syria for their release, and had boarded minibuses to travel to Damascus with a military escort.