AUSTRALIANS who travel to Syria or Iraq will have to prove to authorities on their return that they were not involved in terrorism in a dramatic change to counterterrorism laws to be taken to Cabinet next week.

The reversal of the burden of proof will mean anyone travelling to a declared zone must prove to a court in Australia that they had not been involved with a terror group, rather than police having to prove they were.

In a rewriting of the counterterrorism laws introduced by John Howard in 2005, the definition of terrorism will be fundamentally changed with new laws to give greater powers to police to arrest and detain people to prevent a terrorist act.

It is believed that following the first round of national security laws introduced two weeks ago to boost the powers of the spy agencies, Attorney-General George Brandis will take a second tranche of counterterrorism laws to cabinet next week. It will involve more than 30 changes to the commonwealth criminal code, the Crimes Act and Foreign Insurgents and Recruitment Act.

media_camera Cartoon: Warren

The most significant change will be a new provision to declare that any Australian who travels to a declared zone, such as Syria or Iraq, will be “presumed” to be involved in terrorism.

While some Australians such as alleged terrorists Khaled Sharrouf and Mohamed Elomar have boasted of their terrorist acts, counterterrorism police and spy agencies are deeply concerned about the difficulty in gaining evidence against others who have hidden their activities overseas.

Sweeping changes will also be introduced to give police greater powers to lock up people believed to have links with terror groups or who were actively planning imminent attacks — within 14 days — on home soil under preventive detention provisions.

It is believed the Act, which currently restricts police from arresting people unless they “believe on reasonable grounds” they are guilty of a terrorism-related offence, will be changed to “suspecting” they were involved.

It is also believed the definition of terrorism will be broadened to capture individuals or organisations who promote terrorism.

The association provisions in current laws will be broadened to allow police to arrest people known to have links to organisations which promote terrorism or may be involved in planning terrorist acts.

Changes will also be made, as first flagged by The Daily Telegraph last month, to the proscribing of terrorism groups in Australia to broaden the definition and include organisations who promote or encourage terrorism.

Senator Brandis also wants to remove the 10-year sunset provisions on the counterterrorism laws, due to expire next year, and enshrine them in perpetuity in a sign the government believes the risks will be long-lasting.

‘‘Islamic community leaders are our partners and allies seeking to eliminate the radicalised few ... who pose a specific concern to Australia’s security,” Mr Brandis said.