Poppy wreaths and a banner carrying the name of a murdered police officer were among items placed on contentious republican bonfires ahead of them being lit on Sunday night.
The name of constable Ronan Kerr, who was murdered by dissident republicans in Omagh in 2011, was clearly visible on the side of a pyre in the Bogside area of Londonderry on Sunday evening.
Union flags, Israeli flags and British military insignia, including that of the Parachute Regiment, were also tied to the fire prior to it being lit late on Sunday night.
Republican and loyalist bonfires continue to be a source of controversy in Northern Ireland.
Bonfire builders from both communities have provoked anger in the past by burning symbols associated with the other’s culture on their fires.
The PSNI said it was aware of a banner on the Bogside bonfire that was making threats towards police officers and a member of the public.
Chief Superintendent Darrin Jones said: “The display of this material has been perceived as both offensive and distasteful.
“An evidence-gathering operation was in place during this incident and we will now review this to establish if any offences occurred. If any offences are detected, a full police investigation will be carried out.”
He urged anyone with information to come forward.