Two males have been arrested and charged with conspiring to conduct an act in preparation for a terrorist attack, following raids in the south-west of Sydney on Thursday morning.

One of the alleged plotters is a 15-year-old boy, while the other is a 20-year-old man. 

The plots relate to plans to allegedly kill a random member of the public in Sydney’s CBD, and to attack a government building in the same area.

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The boy is from Georges Hall while the man is from Raby, and the arrests were conducted as part of the ongoing Operation Appleby investigation into the alleged planning of a terrorism attack in Australia, police said.  

The 15-year-old-boy was 14 at the time of the alleged offence. 

The AFP also confirmed it would charge three others – already in custody for terror offences – with “related and unrelated matters”.

In addition to the arrests, the AFP and NSW police conducted three search warrants at Bankstown, Merrylands and Wiley Park on Thursday morning. 

The charges all relate to material seized during search warrants conducted by Operation Appleby in December 2014.

Mr Phelan said the men were influenced by people from abroad. Photo: Getty

“It will be alleged in court (that) the men (charged) were involved in formulating documents connected with preparations to facilitate, assist, or engage a person to undertake a terrorist act,” an AFP statement detailed. 

NSW deputy special operations police commissioner Catherine Burn said there were two alleged plots that led to the charges.

She said it was “disturbing” that a teenager had been involved. 

“In broad terms, the first one is as we have alleged – it would involve a random person,” Ms Burn said. 

“The second one we will allege may have involved an attack on a Government building, whether that may be AFP or police, we don’t know.”

The 20-year-old man will appear in Campbelltown Local Court on Thursday afternoon. 

AFP deputy commissioner Michael Phelan alleged the men were influenced by people from overseas. 

“Certainly right from the beginning, this whole Appleby crew have been – they’ve had influence from people overseas and as those people have come in and out we absolutely deem that they have the capability and capacity to be able to carry out – and the intent to carry out an attack here in Australia,” he said. 

The Department of Corrective Services will consider how the 15-year-old boy should be dealt with if he is refused bail when he faces court. 

Ms Burn said she was not aware of a connection between the boy arrested on Thursday and the Parramatta shooter, Farhad Jabar, who was killed after he allegedly fatally shot police worker Curtis Cheng. 

However, she did reveal that: “the people who were involved with the murder of Curtis Cheng are associates of these people (arrested today).”