In the largest anti-terrorist action in Australian history, the nation's law enforcement arrested 15 suspected terrorists around Australia after they obtained intelligence pointing to a planned ISIS attack within the country.

More than 800 federal and state police officers executed more than a dozen arrest warrants for suspected terrorists in Sydney as well as the cities of Brisbane and Logan on Wednesday, according to the Associated Press.

Andrew Colvin, Australian Federal Police Deputy Commissioner, said the people arrested were suspected of orchestrating violent acts in Australia. Reuters reports the group had allegedly planned to abduct and execute a random citizen of Sydney, record it and drape them with ISIS' black flag.

"That's the intelligence we received," said Prime Minister Tony Abbott. "The exhortations, quite direct exhortations, were coming from an Australian who is apparently quite senior in ISIL to networks of support back in Australia to conduct demonstration killings here in this country."

One of the men arrested, Omarjan Azari, 22, appeared in court charged with conspiracy to commit a terrorist act and, according to officials, will remain in custody until a November hearing.

The suspect's attorney, Steven Boland, did not apply for bail for his client but he told the court that his client's arrest was based on one phone call.

The man he allegedly spoke with is Mohammad Ali Baryalei, ISIS' senior Australian operative in Syria, according to the Sydney Morning Herald. The 33-year-old former bouncer and part-time actor has been recruiting young Australians for ISIS since before he left for Syria.

The news of plans for such a gruesome attack prompted the nation's terrorist alert to be raised right before the arrests and has prompted politicians to condemn the actions.

"The reports of what these people were allegedly preparing are truly shocking. Like every Australian it makes me sick to the stomach to think that some of the images that we associate with other parts of the world could possibly occur in our streets," said opposition leader Bill Shorten.