Approximately €8,000 worth of cocaine was seized from a premises on the Freshford Road on Sunday evening.
The address on the outskirts of the city was searched as part of a planned garda operation which has targeted a number of locations around the city and county in recent days.
A man in his early twenties was arrested on Monday and detained at Kilkenny Garda Station where he is being questioned by detectives.
On Friday night a further six premises were searched at a number of locations and a number of seizures of cannabis and cocaine were made.
One male in his forties was also detained in relation to the sale and supply of cannabis.
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