The street value of drugs seized in the Athlone area in the past number of days has risen to €450,000.
Last week, gardaí arrested a man after a quantity of drugs were found in a car at Doon.
However, follow-up searches, which have been taking place over the weekend, have uncovered a large amount of amphetamines, crack cocaine and cannabis.
The drugs were found by gardaí who had been combing areas of open ground and woodland.
Yesterday, the man arrested appeared at a Special Sitting of the District Court in Nenagh, he was remanded in custody and will appear in court in Ballinasloe next week.