Invercargill City Council says it is "shocked" by vandalism at Eastern Cemetery on the weekend.
Parks Manager Robin Pagan said dozens of flower vases, tributes and ornaments placed on graves had been removed from the memorials and then smashed.
Staff discovered the destruction when they arrived at work this morning, and called police, he said.
"This is going to be very distressing for the families who have lost their loved ones.
"Even though the headstones were not damaged, many of the tributes left by friends and family have been completely destroyed."
He said it was a "senseless and hurtful act".
Pagan said staff would today be working to clean up the area.