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KENT Police say the contents of a jar removed from a flat in Faversham Road, Kennington, near Ashford, on Wednesday posed no risk to the public.
It was thought to have contained a potentially hazardous radioactive substance and led to a full-scale alert.
But police say analysis of the jar has revealed it contained "a granite type rock that has a natural background radiation signature".
A spokeswoman added: "The level of radiation posed no risk to the public."
The emergency services had been alerted by a gas man who found the jar in a cupboard under the stairs in the flat.