Counter-terrorism arrests: what we know

OPERATION APPLEBY COUNTER-TERRORISM DEVELOPMENTS:

* A 15-year-old boy from Georges Hall and a 20-year-old from Raby both charged with conspiracy to conduct an act in preparation for a terrorist act.

* The teen is expected to face Parramatta Children's Court on Thursday.

* The 20-year-old is expected to face Campbelltown Local Court on Thursday afternoon.

* Homes raided in Bankstown, Wiley Park and Merrylands. No arrests made at these homes.

* Three men, believed to all be inmates at the Goulburn Supermax prison, have also been arrested.

* They are expected to be charged and to also face court on Thursday afternoon.

* The trio are already before the courts on related and unrelated matters.

* All arrested men are associates of those connected with the murder of police accountant Curtis Cheng outside Parramatta police headquarters in October.

* Charges relate to material seized by Joint Counter Terrorism Team officers in December 2014.

* Police seized documents in December 2014 that "talk about a plan" naming government buildings "specifically the AFP building".

* Thursday's arrests relate to a further alleged plot.

* The original plot involved the alleged planning of an attack on a random member of the public.

* Police say the second plot "may have involved an attack on a government building, whether that be AFP or police".

* Both plots relate to activities allegedly planned in 2014 and police say there was no immediate threat at the time of Thursday's arrests.

* The Joint Counter Terrorism Team has made 11 arrests as part of Operation Appleby, which began in 2014.