Ketamine and herbal cannabis were discovered by Revenue officers.
Over €260,000 worth of drugs has been seized in the midlands.
Revenue officers discovered 3kg of ketamine and over 4.6kg of herbal cannabis, with an estimated value of €266,000, during an examination of parcels at a premises in Athlone.
The drugs originated from the Netherlands and Spain, and were destined for addresses in Dublin and Kildare.
The seizure is part of an ongoing investigation targeting organised crime groups and the importation, sale and supply of illegal drugs.