The official spokesman of the Islamic State terror group has purportedly issued a chilling message calling on his followers to murder Australians in ghastly ways.

In what the Prime Minister's office said was being regarded as a 'genuine threat' by the nation's security agencies, senior IS leader Abu Mohammed al-Adnani on Monday released an audio message specifically calling for attacks on people of a number of nationalities, including Australians.

al-Adnani said: 'If you can kill a disbelieving American or European – especially the spiteful and filthy French – or an Australian, or a Canadian, or any other disbeliever from the disbelievers waging war, including the citizens of the countries that entered into a coalition against the Islamic State, then rely upon Allah, and kill him in any manner or way however it may be.'

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Threats: Abu Mohammed al-Adnani, pictured (above) in a terror message posted on YouTube in July 2012.

Sick threats: The Islamic State terror group has released videos of a militant beheading three Westerners in recent times.

Terror suspect Omarjan Azari, 22, pictured (above) being taken away from court. He was charged with conspiracy to commit terrorism last Thursday.

Heavily armed NSW Corrective Services officers prepare to transport accused terrorist Omarjan Azari from Central Local Court after appearing on a charge of conspiracy to prepare for a terrorist act.

'Do not ask for anyone’s advice and do not seek anyone’s verdict.'

'Kill the disbeliever whether he is civilian or military, for they have the same ruling.'

In the statement, Al-Adnani purportedly implored his followers to commit a number of graphic crimes against 'disbelieving American (sic), Frenchman, or any of their allies'.

'Smash his head with a rock, or slaughter him with a knife, or run him over with your car, or throw him down from a high place, or choke him, or poison him.'

And in a lengthy series of rhetorical questions addressed to the 'soldier of the Islamic State', he appeared to question Australia's involvement in the Middle Eastern conflict.

'Why have the nations of disbelief entrenched together against you?' he asked.

'What threat do you pose to the distant place of Australia for it to send its legions towards you? What does Canada have anything to do with you?'

The militant's message follows the disruption of an alleged Sydney beheading plot in the nation's largest ever terror raids last Thursday.

In a statement, a spokesman for the Prime Minister told Daily Mail Australia the government believed the terrorist's statement was real.

'Australian agencies regard the statement issued today by ISIL calling for attacks against members of the international coalition, including Australians, as genuine,' the spokesman said, using an alternative name for the IS terror group.

Police remove a sword as part of evidence found at a residential property in the suburb of Marsfield, in Sydney last Thursday.

Raids: Australia witnessed its largest ever terror raids last Thursday, when Australian Federal Police and NSW Police agents swarmed a number of properties across Sydney. Raids were also conducted in Brisbane.

Addressing the terror threat to the nation, Prime Minister Tony Abbott today said that Australia's 'delicate balance' between freedom and security may have to tilt towards security 'for some time to come'.

A U.S. State Department notice described al-Adnani, born under the name Taha Sobhi Falaha, as the 'official spokesman and a senior leader of ISIL'. He is the 'main conduit for the dissemination of official messages', the notice said.

Al-Adnani's chilling threat came as the Federal Government outlined its plans for new anti-terror legislation on Monday afternoon.

Mr Abbott told Parliament he could not promise that 'hideous events' will never take place in Australia.

'Regrettably, for some time to come, Australians will have to endure more security than we’re used to, and more inconvenience than we’d like,' he said.