US-backed Kurdish fighters in Syria are urging Canberra to repatriate the Australian Islamic State jihadis in their custody.

"However, the Morrison government is determined to deal with these people as far from our shores as possible and ensure that any who do return do so with forewarning and into the hands of appropriate agencies," a spokeswoman for Home Affairs Minister Peter Dutton told The Sydney Morning Herald and The Age.

The Kurds, part of the Syrian Democratic Forces, are battling IS in their last enclave and currently hold about 800 militants of various nationalities.

US President Donald Trump has urged various countries to take back their nationals, but other countries have followed Australia's example by stripping them of their citizenship so they can return home.

Many think they should be tried where their crimes were committed in Iraq and Syria. Australian Neil Prakash is being held in Turkey where he is being prosecuted by Ankara and has had his Australian passport cancelled.