Prime Minister Scott Morrison has rebuffed a United States offer to rescue Australian families of IS fighters from Syria.

The US has offered to help its coalition partners by facilitating the return of foreign fighters and their families to their countries of origin.

But the prime minister is unmoved.

"Our assessment is done on a case-by-case basis and our assessments at this point have not changed," he told reporters in Adelaide on Monday.

READ MORE Turkey pressures Australia to take back captured IS fighters, families

Mr Morrison has consistently argued Australian officials should not be placed in danger in order to remove the women and children in the conflict zone.

Asked what reason there could be to reject the offer, given it would guarantee Australian officials would not be placed at risk, Mr Morrison said: "I don't engage in hypotheticals on national security issues."

"National security issues are very serious and you have to deal with the cases as they present - not hypotheticals - but as they present in reality and that's how we'll deal with each and every one of them."

Foreign Minister Marise Payne said the situation in Syria was extraordinarily complex, difficult and dangerous.

"The Turkish invasion of Syria has only exacerbated those problems," she told reporters in Sydney.

"Australia has been very clear that while we understand the predicament in which these people find themselves, and certainly understand the challenges and difficulties for their families, we will be very, very careful about any steps that we take in relation to that because we won't put any further Australians in danger."

AAP

Home Affairs Minister Peter Dutton has previously said many of the women, who are wives of IS fighters, posed serious security risks if they returned to Australia.

Mat Tinkler from charity group Save the Children said the Australian government had run out of excuses and should immediately accept the US offer.

"This is a welcome but time-limited offer from the United States to the Australian government," he said.

"The Australian government should take responsibility, immediately accept this offer and bring the Australian women and children home."

More than 60 Australians are in the al-Hawl camp, including 44 children, most of whom are aged under five.

"The offer from the US comes as winter threatens the camp and in particular the many malnourished and sick children it shelters," Mr Tinkler said.

"We know how desperate the situation is in this camp. Children's lives are at stake. The urgency of the situation cannot be overstated."