Dog walkers who exercise their pets at one of Norfolk's best loved historic sites are being warned to be vigilant.
Norfolk Archaeological Trust said in a post that it had received unconfirmed reports about dogs being poisoned by meat balls laced with slug pellets.
The post said: "We have no further details at present but advise all dog walkers to be extra vigilant at Burgh Castle Fort.
"Norfolk Constabulary are involved with the investigation and the Parish Council are aware. Please report to us and the police any suspicious activity or if you find anything of concern, thank you."
The alarm was raised after a dog fell seriously ill. It was taken to the vets and made a full recovery.
At the time the police said they were treating the incident as an act of animal cruelty and appealed for witnesses.
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