SYDNEY (AP) -- Five Australian teenagers were arrested Saturday on suspicion of plotting an Islamic State-inspired terrorist attack at a Veterans' Day ceremony that included targeting police officers, officials said.
The suspects included two 18-year-olds who are alleged to have been preparing an attack at the ANZAC Day ceremony in Melbourne, Australian Federal Police Acting Deputy Commissioner Neil Gaughan told reporters.
Another 18-year-old was arrested on weapons charges and two other men, aged 18 and 19, were in custody and assisting police.
ANZAC stands for the Australian and New Zealand Army Corps and commemorates the World War I battle in Turkey on April 25.
The arrests took place in Melbourne, where a joint counterterrorism team served a total of seven warrants Saturday morning. Police said they were conducting searches at properties.
Police said they believe the plot was inspired by the Islamic State group, also known as ISIS, and was to have involved "edged weapons."
"At this stage we have no information that it was a planned beheading. But there was reference to an attack on police," Gaughan said. "Some evidence that we have collected at a couple of the scenes, and some other information we have, leads us to believe that this particular matter was ISIS-inspired."
Australia's government has raised the country's terror warning level in response to the domestic threat posed by supporters of the Islamic State group. In September last year, the group's spokesman Abu Mohammed al-Adnani issued a message urging attacks abroad, specifically mentioning Australia.
Federal Police Deputy Commissioner Michael Phelan said at a separate news conference that the teens had links to Numan Haider, an 18-year-old who stabbed two Melbourne police officers and was subsequently shot dead in September. Haider had caught authorities' attention months earlier over what police considered to be troubling behavior, including waving what appeared to be an Islamic State flag at a shopping mall.
Phelan said the teens arrested on Saturday had been on officials' radars for months, but the investigation ramped up when it appeared they were planning a specific attack.
"This is a new paradigm for police," Phelan said. "These types of attacks that are planned are very rudimentary and simple. ... All you need these days is a knife, a flag and a camera and one can commit a terrorist act."
Prime Minister Tony Abbott has warned that the terrorism threat in Australia has escalated with one-third of all terrorism-related arrests since 2001 occurring in the last six months. At least 110 Australians have gone to Iraq and Syria to fight alongside extremists, and the nation's security agency is juggling more than 400 high-priority counterterrorism investigations -- more than double the number a year ago.
In February, two men were charged with planning to launch an imminent, Islamic State-inspired terrorist attack after authorities said they appeared on a video threatening to stab the kidneys and necks of their victims. And in September, a man arrested during a series of counterterrorism raids was charged with conspiring with an Islamic State leader in Syria to behead a random person in Sydney.
In December, Man Monis, an Iranian-born, self-styled cleric with a long criminal history, took 18 people hostage inside a cafe, forced them to hold up a flag bearing the Islamic declaration of faith and demanded he be delivered a flag of the Islamic State group. Monis and two hostages were killed.
Abbott said the latest alleged plot was at an advanced stage of planning, prompting police to swoop. Still, he urged the public to participate in ANZAC Day events as usual.
"The best sign of defiance we can give to those who would do us harm is to go about a normal, peaceful, free and fair Australian life," he said. "And I say to everyone who is thinking of going to an ANZAC Day event, please don't be deterred. Turn up in the largest possible numbers to support our country."