The RSA has condemned the desecration of Anzac war graves in London as a "wanton act of vandalism".
"Such an act is appalling and can never be justified in any way," said New Zealand Returned and Services Association chief David Moger.
"It is completely disrespectful to all those who gave their lives in service."
It emerged yesterday that the graves, dedicated to New Zealand soldiers who died in World War I, had been defaced with spray paint.
The vandalism was discovered at Harefield churchyard in Hillingdon, west London.
"Those whose gravestones they defaced demonstrated the Anzac spirit, values of courage, commitment, comradeship and compassion," Mr Moger said. "We can only hope that those who committed this crime find the courage to step forward, accept responsibility for their actions and make reparations."
He said the RSA had not had any contact from family members associated with the graves, but it understood the Commonwealth War Graves Commission was working on repairing the damage.
London councillor Jane Palmer was moved to tears when she discovered the vandalism yesterday. She took photos of the graffiti attack and reported it to police.
There are 120 World War I graves at Harefield Park (St Mary) Churchyard for Kiwi and mainly Australian troops who died at the nearby No 1 Australian Auxiliary Hospital.
Each grave is marked by scroll-shaped headstones, chosen by the staff and patients at the hospital.
"In tears this morning at this desecration," Ms Palmer wrote as she posted photographs on social media yesterday.
The Met Police have asked for witnesses or anyone with information to come forward.
It is the second such incident this year. A memorial in the cemetery was sprayed with paint and the Australian flagpole cut into on the eve of the Gallipoli centenary, the Mirror reported.
Ms Palmer said she had had offers to help clean the headstones, and though she had been "touched by your kindness" the Commonwealth War Graves Commission was taking up the task.