A man who provided a revolver used to kill a state police employee in an Islamic State group-inspired attack in Sydney in 2015 has been sentenced to 17 years in prison.

A 15-year-old boy was shot dead by police moments after he killed Curtis Cheng with a 0.38 Smith & Wesson as the accountant walked from the New South Wales state police headquarters in central Sydney after work.

Talal Alameddine refused to stand for Justice Peter Johnson who sentenced him in the New South Wales Supreme Court on Friday to serve a minimum 13 ½ years behind bars.

Alameddine had pleaded guilty to recklessly possessing an object connected with a terrorist act and supplying a pistol. The maximum penalty for each offense is 30 years in prison.