Australia's prime minister says hurdles remain to repatriating three orphaned Australian children of a convicted terrorist from a Syrian refugee camp and national security interests must come first.

Prime Minister Scott Morrison said Tuesday that Australia is working with the Red Cross to repatriate three children and two grandchildren of slain Islamic State group fighter Khaled Sharrouf from the camp in northeastern Syria.

Morrison is campaigning for his conservative coalition to be re-elected for a third three-year term on May 18. He argues that his government is stronger on national security and border protection than the center-left opposition Labor Party.

Opposition leader Bill Shorten says the offspring of the Sydney-born terrorist should not become an election issue.