Prime Minister Tony Abbott on Monday warned Australians fighting with extremists in the Middle East they face lengthy jail terms if they return home as the government tightens counter-terrorism laws.
"My unambiguous message to all Australians who fight with terrorist groups is that you will be arrested, prosecuted and jailed for a very long time," Abbott told parliament in a statement on national security.
Australia is targeting domestic extremists as well as citizens who fight overseas with violent jihadist groups in Syria and Iraq before returning home.
"Our laws are being changed to make it easier to keep potential terrorists off our streets," Abbott said after the biggest security crackdown in Australian history last Thursday saw more than 800 police officers raid some 30 homes.
A 22-year-old man was charged with planning a terrorist act.
The government said it had foiled a plot by Islamic State (IS) jihadists to carry out gruesome "demonstration executions" in Australia.
"An Australian ISIL operative instructed his followers to pluck people from the street to demonstrate that they could, in his words, 'kill kafirs (non-believers)'," Abbott said, using an alternative acronym for the group.
Sixty Australians are known to be fighting in Iraq and Syria, more than 20 have already returned to Australia while at least another 100 actively support the jihadists, Abbott said.
The government considers current legislation inadequate to fight the threats from groups such as the Islamic State and is pushing two bills through parliament this week.
Attorney-General George Brandis has drawn up a bill to give security agencies greater powers and another to deal with the threat from so-called "foreign fighters" returning from combat with extremists abroad.
"Legislation to create new terrorist offences and to extend existing powers to monitor or to detain terror suspects will be introduced this week," the prime minister said.
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Abbott added that if the security forces made a case for further powers his government's inclination would be to back them.
"As well, legislation requiring telecommunications providers to keep the metadata they already create and to continue to make it available to police and security agencies will be introduced soon," he said.
- 'No-go areas' -
Under the new powers, which are expected to have broad bi-partisan support, it will be illegal for an individual to intentionally counsel, promote, encourage or urge a terrorist act, according to Brandis.
The bills will also allow for bans on visits to cities or regions where terror groups are declared to be active. People travelling to such "no-go areas" without a valid reason could face prosecution.
"It will be an offence to be in a designated area, for example Raqa in Syria, without a good reason," Abbott said.
He regretted that "for some time to come, Australians will have to endure more security than we're used to, and more inconvenience than we'd like.
"Creating new offences that are harder to beat on a technicality may be a small price to pay for saving lives and for maintaining the social fabric of an open, free and multicultural nation," he said.
The crackdown has provoked little protest from rights activists and been generally supported by the opposition Labor party.
The government has earmarked an additional Aus$630 million (US$563 million) to bolster security and stepped up protection at public places across the country, including parliament.
Abbott flies Tuesday to New York to attend a special session of the security council chairmed by US President Barack Obama to deal with the threat of foreign fighters.
Canberra has also committed 600 troops and aircraft to the US-led coalition gearing up to destroy the IS organisation in Iraq.