Independent senator Jacqui Lambie and other MPs have criticised Khaled Sharrouf and Mohamed Elomar, who are believed to have died in Iraq.
Suspected dead foreign fighters Khaled Sharrouf and Mohamed Elomar have been labelled "dirty, disgusting terrorist grubs" by outspoken independent senator Jacqui Lambie.
The Sydney men are believed to have been killed in Iraq during drone strikes on Mosul.
"They're grubs and I don't really care about them," she told reporters in Canberra.
Liberal Democrat David Leyonhjelm said there was just one message from the deaths: "Don't go and if you do go, be done and get killed and don't come back again".
Fellow crossbencher Nick Xenophon said it was problematic to know whether Sharrouf and Elomar could have been brought back to Australia for prosecution under planned new terror laws.
"If they were captured then I think rather than stripping them of their citizenship they should have been brought back here and throw away the key," he told reporters.
"Let them die in prison as pathetic old men with a spiteful hatred that makes no sense."
Sharrouf's wife and children are believed to have been negotiating their return to Australia before his death.
Nationals MP Andrew Broad said there should be a distinction between the mother and her children.
"The children are different, the children are minors," he told reporters.
"Just because you're a woman doesn't mean you're immune from the laws of the country.
Liberal MP Dennis Jensen hinted the children should not be penalised for their parents decisions.
"I think you've got to be very careful about visiting the sins of the father on the son, so-to-speak," he said.