Pest control officers sealed off a seafront public garden which has become infested by rats.
The sunken gardens near the Peace Statue, on the boundary of Brighton and Hove, have been closed.
Poison has been put down in locked traps in a bid to kill the rats and stop the infestation spreading.
Many residents have reported seeing rats darting in and out of the gardens' hedgerows next to the seafront esplanade.
Rodney Posner, owner of The Meeting Place cafe on Hove seafront, near to the gardens, said: "It is disgusting. There are lots down there.
"I had a look in there and I saw a few running round. It seems to have been going on for a while.
"Lots of my customers have come up to me and said they have just walked through the gardens and seen a rat.
"I haven't seen any round here. If I see one coming into here I will panic but I think they are content in the garden.
"At least the council has sealed off the area and put poison down now."
A woman from Hove, who did not want to be named, said: "I have seen rats there a few times. They were quite big.
"It was quite a shock because you associate rats with rubbish and dirt.
"It's a shame when all this money has been spent redeveloping the seafront and there is this one bit left undeveloped and it's full of rats.
"I was just strolling past there the other day and this rat ran out. It was not very nice."
Pest control officers are satisfied the infestation will not spread further down the seafront towards the new £750,000 children's play area which is more open-plan, with few places for rats to hide.
They do not think there is a serious risk to public health.
Brighton and Hove City Council sent in its pest control team after complaints from the public.
A spokeswoman said: "We believe the rats have been encouraged by people feeding seagulls and pigeons. We wish they wouldn't do it.
"There is no connection with food outlets. They are away from the situation and the seafront bins are emptied regularly."
She said officers would check to make sure the rats had been destroyed by the poisoned bait.
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