Up to 50 Australians fighting overseas with terror groups could lose their citizenship under new government rules.
The government will soon introduce legislation allowing it to strip dual citizens fighting in Iraq or Syria of their Australian citizenship.
People working in Australia to support terror groups would also be targeted by the changes.
Concern has been rising since mid-2014 about Australians fighting for the Islamic State militant group.
Prime Minister Tony Abbott said the legislation, due to come before parliament in June, was "all about combating terrorism".
"We face an increasing threat from those in our midst who would do us harm," Mr Abbott said at a press conference in Canberra on Tuesday.
Conflict zones
He said at least 100 Australians were fighting with terror groups in the Middle East, and as many as half of them had dual citizenship.
Another 150 people in Australia were known to be supporting such groups, while Australia's intelligence agency, the Australian Security Intelligence Organisation (ASIO), was investigating about 400 high-priority terrorist cases.

Up to 50 Australians fighting overseas with terror groups could lose their citizenship under new government rules.
The government will soon introduce legislation allowing it to strip dual citizens fighting in Iraq or Syria of their Australian citizenship.
People working in Australia to support terror groups would also be targeted by the changes.
Concern has been rising since mid-2014 about Australians fighting for the Islamic State militant group.
Prime Minister Tony Abbott said the legislation, due to come before parliament in June, was "all about combating terrorism".
"We face an increasing threat from those in our midst who would do us harm," Mr Abbott said at a press conference in Canberra on Tuesday.
Conflict zones
He said at least 100 Australians were fighting with terror groups in the Middle East, and as many as half of them had dual citizenship.
Another 150 people in Australia were known to be supporting such groups, while Australia's intelligence agency, the Australian Security Intelligence Organisation (ASIO), was investigating about 400 high-priority terrorist cases.

Mr Abbott said the government would ensure no-one became stateless and that any decision to strip citizenship from an Australian would be subject to judicial review.
People convicted of terrorism offences, regardless of citizenship, would be jailed.
If they no longer had Australian citizenship, they would likely be deported, he said. But someone could lose their citizenship without being convicted of an offence.
The new laws will be based on overseas models, in particular those in the UK.
"Australia is not acting alone here and we are not ahead of the pack ... We have taken advice from our partners," Mr Abbott said.
The legislation might also hold ramifications for second-generation Australians because the government is looking at whether it would strip them of citizenship if they were entitled to citizenship of another country but did not actually have it.