Two men were charged Thursday in connection with a terror plot that Australia 's prime minister said involved plans to carry out a public execution . Prime Minister Tony Abbott said authorities obtained intelligence about a `` demonstration killing '' -- a killing , Australian media reported , in which alleged assailants planned to kidnap a member of the public , behead the victim and then drape him or her in an ISIS flag . The foiled plot comes just days after the country raised its terror alert to high and in the midst of Australia committing to helping the United States and a broad international coalition to beat back the Islamic State , or ISIS . The militant group has been slaughtering people and taking over villages in Syria and Iraq . One of its members beheaded two Western journalists and an aid worker -- brutality that was videotaped and broadcast throughout the world . ISIS vows that it will stop at nothing to create a caliphate governed by the intensely strict Sharia law . Suspects arrested , detained . Earlier Thursday , at least one person had been arrested and charged with terrorism offenses and another 14 were detained as police conducted more than two dozen searches in Sydney , acting Federal Police Commissioner Andrew Colvin said at a news conference . Hours later , police said nine people who were detained have been released . A 24-year-old man from Merrylands has been charged with possession of ammunition without a license and unauthorized possession of a prohibited weapon , authorities said . Another man has also stood in court , charged with conspiracy to commit acts in preparation of a terrorist act and financing terrorism , police said , and two women were issued notices to appear later in court . Their names have not been released . Authorities declined to give details about the threat , citing an ongoing operation . But Abbott told reporters that intelligence revealed that Islamic militants inside Australia were planning to kill . `` The exhortations , quite direct exhortations , were coming from an Australian who is apparently quite senior in ISIL ( Islamic State ) to networks of support back in Australia to conduct demonstration killings here in this country , '' he said . Early morning raids . More than 800 law enforcement officials fanned out across Sydney suburbs as part of a coordinated operation to serve 25 search warrants . `` Today 's operation reflects the reality of the threat we actually face , '' said Andrew Scipione , commissioner of New South Wales Police . A second series of searches were carried out in Brisbane , Scipione said . Those searches were connected to the arrests earlier this month of two men in Brisbane accused of recruiting and financing foreign fighters to Syria . The commissioner said authorities are looking for links between the Sydney operation and the one in Brisbane . Meanwhile , police presence has been increased at Parliament because of security threats , Abbott told Channel 7 on Friday . Citing an intelligence review carried out in recent days , Abbott said federal police will be taking over security inside and outside of Parliament . Terror alert raised to 'high ' Australia last week raised its terror alert level to `` high '' for the first time since the national alert system was introduced in 2003 . It 's the second-highest alert level . According to the four-level system , a reading of `` high '' means a terrorist attack is likely . The decision to raise the level was foreshadowed by the departing director-general of the Australian Security Intelligence Organization ( ASIO ) last week . David Irvine said the threat level had been building in Australia over the last year , due to the increasing influence of Australian jihadists who had gone to fight for ISIS in the Middle East and then returned home . According to the Sydney Morning Herald , Irvine said more than 20 Australians had returned home after fighting in Iraq or Syria , and about 60 Australians are currently fighting with extremist groups . Australia joins anti-terror coalition . This week , the Australian government was one of 40 nations that agreed to contribute to the fight against ISIS , the terror group that calls itself the Islamic State . The government has agreed to send military advisers to Iraq , and it will deploy a number of aircraft , including fighter jets , to the United Arab Emirates . It also will also help to stem the humanitarian crisis . Australian combat troops will not participate in ground fighting , according to Abbott .
Security ramped up at Parliament , PM Tony Abbott says . Police say charges were filed against two men . Abbott says intelligence pointed to possible `` demonstration killing '' by militants .