Australian authorities are preparing for a flood of foreign fighters, and their families, returning from Syria and Iraq who could pose a threat to the community.

As Islamic State suffers military defeats, Justice Minister Michael Keenan says jihadis who aren’t killed on the battlefield will want to continue the struggle elsewhere.

“This will include a number of Australians – all of whom have lengthy military experience, a deepened commitment to the ISIL cause, and networks of like-minded comrades from around the world,” he told the Lowy Institute in Sydney on Wednesday.

“We must be ready with strategies to protect the safety of our communities and the welfare of children.”

Mr Keenan confirmed as many as 68 Australians have been killed in Syria and Iraq, up from 35 in July 2015.

A total of 51 people have been charged as a result of 21 counter-terrorism operations, with 38 of them now before the courts.

That number includes a woman and two 16-year-olds.

The government has cancelled, refused or suspended 190 passports, he said.

“All these figures speak to the scale of the problem, and each of them represents new challenges for investigators, prosecutors and legislators.”