Three men remain in garda custody this morning in connection with the seizure of drugs worth over 300,000 euro, in two locations in the Killasser / Swinford area on Saturday evening last.
Two houses were searched following surveillance by the Divisional Drugs Unit.
Cannabis plants at different stages of growth were discovered.
Three men, aged 44, 27 and 23 were arrested at the scene in connection with the investigation.
They are being questioned at Ballina Garda Station.
Investigations are continuing.