Police Commissioner Peter Marshall has ordered police officers to end a long-standing custom of accepting discounts at fast food outlets.
AAP reports he was responding to publicity about officers receiving discounts from McDonald's and Subway when in uniform.
He said police reputation was too important to be compromised by such perks and officers accepting discounted food could be subject to code of conduct investigations.
Mr Marshall said police must not accept gifts for simply doing a good job.
"It is totally inappropriate for a police officer in uniform to consider receiving discounted food from any outlet,'' he said.
"Police officers should pay full price or walk away - it is as simple as that."
AAP reports the issue of fast food discounts for police was previously raised in 2007, when the Police Association conceded it attracted cut-price security for the outlets.