Michelle O'Neill has condemned thugs who placed poppy wreaths on a bonfire in Londonderry, while Arlene Foster has hit out at those who placed an effigy of a hanged Orangeman on another.
The DUP First Minister described the effigy as a "disgraceful hate crime".
"The ignorant people behind this display of hatred and racism should be pitied," she wrote on Facebook.
"When all you have to say is to attack someone else's culture and identity, then your own 'culture' is really bereft of any meaning or worth."
The Deputy First Minister said those responsible for the various displays were acting against the wishes of the local community.
The wreaths were placed on a bonfire built in Curryneirin in the Waterside area.
Wreaths had recently been stolen from a nearby war memorial.
Ms O'Neill said: "There can be no place in society for the burning of flags and emblems.
"Those involved in bonfires in Derry do not reflect republicanism. They are also acting in contrary to the wishes of the local community.
"We must all continue to work to end these displays of hate."
The bonfires are lit to mark the Catholic Feast of the Assumption and to mark internment during the Troubles.
On one of the biggest fires, in the Bogside, a picture of the Queen was attached to the structure before it was torched on Saturday night.
Union flags, Northern Ireland flags and a US and Israeli flag were also placed on the stacks of wooden pallets, as were flags of the Parachute Regiment - the regiment responsible for the Bloody Sunday shootings in the city in 1972.
PSNI Supt Gordon McCalmont said officers would investigate the incident.
He said: "Police are aware of images of poppy wreaths and other items on bonfires and recognise the hurt this will have caused to individuals.
"Police have commenced an investigation into this."
Ahead of the fire, DUP representative Gary Middleton tweeted: "This is disgraceful and utterly insulting to the war dead. There needs to be leadership shown in this community. Poppy wreaths were stolen from the war memorial in Londonderry recently.
"Those who place wreaths on bonfires clearly have a warped mindset."
Yesterday, Sinn Fein's Martina Anderson added her condemnation.
She said: "The appearance of poppy wreaths on a bonfire in Curryneirin was wrong and must be condemned.
"Everyone has a right to remember their dead in a respectful and dignified manner and the theft and desecration of these wreaths goes totally against that."
Ulster Unionist councillor Darren Guy said the images were "absolutely despicable".
"To do it on the anniversary of VJ Day, which marked the end to hostilities in the Second World War which delivered us freedom from fascism, is reaching a new low, even for militant republicanism," he said.
He added: "To further emphasise their hatred of all things British, those filled with sectarian hatred also burned images of the Queen, Northern Ireland supporters' flags and an effigy resembling a member of the Orange Order."