A dog walker came across this rabbit poison, seen on the left, at about 7.30am on Thursday in an off-leash dog exercise area.

Rabbit poison left in a dog walking area of Hamilton Gardens should never have been there, admits Hamilton City Council.

The discovery of toxic carrots by a dog walker on Thursday morning has prompted the council to temporarily halt its rabbit control operation at the gardens - where bunnies wreck havoc in the cemetery and rose gardens.

Hamilton dog trainer Diana Bird was walking her dog, Spring, about 7.30am on Thursday when she came across the green carrots, laced with rabbit poison pindone.

"I was really concerned when I saw it. I was just walking in and my dog was on a leash and I kept her on a leash."

Pindone works in rabbits by causing blood to coagulate, leading to internal hemorrhaging. It is poisonous to dogs, but would take about 90 pellets to kill them, according to a factsheet by Pest Management Services Ltd.

Bird said there were two more piles of the poison further up the hill, and she warned an approaching dog walker to keep his pooch on a leash.

The council confirmed the poison was in an off-leash dog walking area, and has admitted that placement was "clumsy".

"This is not standard practice for our rabbit control operations at Hamilton Gardens and we acknowledge it was clumsy," community general manager Lance Vervoort said.

The area was off Hungerford Crescent, near the Hamilton East Cemetery.

Vervoort said the carrots should have been removed at 7.30am by staff, yet Bird said that's when she spotted them and then laid a complaint with council's dog control team, at 9am.

"By 10am they had replied that it was going to be looked into and should have been picked up."

The incident follows two dog deaths after visits to Hamilton's Minogue Park in September.

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Investigations into the two deaths revealed a potential harmful algae in a nearby lake, although the cause of death for the two dogs was yet to determined.

The incident has prompted the council to halt its rabbit control operation and reassess its control methods, Vervoort said.

"Our usual practice has been to leave the baited carrots in specific parts of Hamilton Gardens overnight, when the rabbits are active."

The carrots were part of a monthly drop.

"We need to have a look at whether that's the right way to do it, and for the moment, we've stopped our rabbit control operations at Hamilton Gardens."

The council has used pindone in the gardens for 10 years, Vervoort said.

"There have been no dog fatalities related to pest control operations at Hamilton Gardens during this time."