December 27, 2014 Funeral of NYPD Officer Rafael Ramos Photo Credit: Kevin Hagen, Getty Images

NEW YORK (AP) — New York City Police Commissioner William Bratton is urging his employees who attend a slain officer's wake and funeral to refrain from making political statements.

In a memo read at roll calls ahead of the Saturday wake for Officer Wenjian Liu, Bratton says "a hero's funeral is about grieving, not grievance."

That's a reference to hundreds of officers turning their backs to TV monitors displaying Mayor Bill de Blasio delivering remarks at the funeral for Officer Rafael Ramos a week ago.

Police union leaders have accused de Blasio of helping to foster an anti-police atmosphere by supporting demonstrations following the chokehold death of an unarmed black man by a white officer.

Liu and Ramos were ambushed Dec. 20 in their patrol car. Their shooter committed suicide.

(Story by: Mike Balsamo, The Associated Press)