CANBERRA, Australia — Three men inspired by the Islamic State group were charged on Tuesday with planning a mass-casualty attack in Melbourne, Australia’s second-largest city, police said.
The Australian citizens of Turkish descent — Hanifi Halis, 21, and brothers Samed Eriklioglu, 26, and Ertunc Eriklioglu, 30 — were arrested in predawn raids on their Melbourne homes, police said. All had their passports canceled this year on suspicion that they intended to fight with extremists overseas.
The trio communicated with encrypted messages, which made it difficult for police to determine when and where the attack was to take place, Victoria Police Chief Commissioner Graham Ashton said.
‘‘Whilst a specific location was not finalized, there was a view toward a crowded place,’’ where they could kill more victims, Ashton said.
Home Affairs Minister Peter Dutton reacted by calling on Parliament to pass by next month draft cybersecurity laws that would force global technology companies such as Facebook and Google to help police unscramble encrypted messages sent by criminals. Rights advocates have raised privacy concerns.
‘‘The problem that we have now is that the messages being swapped between terror cells and people involved in terrorist activity as well as other significant criminals, they are doing it online through these messaging apps and the police don’t have the ability to get across that technology. That is the significant issue,’’ Dutton told reporters.
The three men were refused bail when they appeared in the Melbourne Magistrates Court late Tuesday charged with planning a terrorist attack. They each could face a life prison sentence if convicted.
Prosecutors told the court the police investigation that began in March involved intercepts of 17,000 phone calls and 10,500 text messages plus 7,800 hours of other covert recordings.
Police allege the men were trying to acquire .22-caliber semiautomatic rifles. Semiautomatic rifles are virtually banned from public ownership under Australia’s tough gun laws designed to reduce mass-casualty shootings.
There’s no link between the latest plot and other attacks and plots in Melbourne. Police have described a fatal stabbing in the city’s central business district on Nov. 9 as an Islamic State-inspired terrorist attack. The attacker was shot dead by police after he killed a 74-year-old man and injured two other people, and he had planned to set off an explosion in his burning pickup vehicle loaded with gas canisters. The Somalia-born Australian had his passport canceled in 2015.
The man who died, well-known coffee shop owner Sisto Malaspina, was given a state funeral on Tuesday.
Australian Federal Police Assistant Commissioner Ian McCartney said 90 people had been charged in 40 counterterrorism investigations since Australia’s terrorism threat level was elevated in September 2014.
‘‘If we had not acted early in preventing this attack, we’ll allege the consequences would have been chilling with potential . . . significant loss of human life,’’ McCartney said of the latest plot.
Four men also were convicted of planning a terror attack in downtown Melbourne around Christmas in 2016.
Ibrahim Abbas was sentenced last month to 24 years in prison after pleading guilty to conspiring in preparation of a terrorist attack involving explosives and knives at Federation Square, a popular downtown restaurant and entertainment precinct.
Abbas had been a prosecution witness against his brother Hamza Abbas and coconspirators Ahmed Mohamed and Abdullah Chaarani. They were convicted of terrorism-related offenses three weeks ago, but they have yet to be sentenced.