Urgent safety checks are being carried out across Rotorua playgrounds after a child was injured when a corroded swing broke mid-air.
However the council says its playgrounds are inspected fortnightly and the damage to the swing set was "difficult to spot".
Peter Gibb told the Rotorua Daily Post he was watching his 9-year-old grandson play on a swing at Owhata's Carroll Place Reserve on Sunday when the chain broke free of the seat.
As the boy fell, he cut his arm on the jagged edge of the rusted bracket that had just given way.
Mr Gibb said he was thankful his grandson hadn't had the chance to swing up as high as he usually managed.
"I shudder to think about the consequences had the swing failed whilst he might have been doing that."
Mr Gibb said the other two swings at the playground were also showing a great deal of rust and wear on their fittings and it didn't appear the playground was being properly maintained.
Concerned the playground was unsafe, and that other parks in Rotorua could be in the same condition, Mr Gibb notified Rotorua Lakes Council on Sunday night. The broken swing was promptly replaced.
Council sport and recreation manager Rob Pitkethley said the council wished the youngster well and hoped he made a quick recovery.
"Children's safety is always a priority in our playgrounds and fortunately we have relatively few such injuries reported."
Mr Pitkethley said Rotorua playgrounds were inspected fortnightly, Carroll Place had been last checked on January 7, with more comprehensive checks happening regularly.
"On investigation it appears the metal on the swing seat has corroded from the inside making it difficult to spot.
"However as a safety precaution we are immediately checking all similar types of swings on our playgrounds and we'll replace any identified as being at risk. We will also be discussing the matter with the swing's manufacturer."
While Mr Gibb was happy the swing was repaired, he thought it was a shame the damage had been missed until now.
"People need to be careful and check the grounds and equipment themselves before letting their children on them, we shouldn't take too much for granted," he said.
Mr Pitkethley urged the public to contact the council immediately if they noticed any damage to playgrounds, or other council facilities, so they could remedy problems as soon as possible.