The drugs were discovered concealed in a consignment of tiles on a Northern Ireland-registered trailer on a ferry from Cherbourg.
Customs officers said it had a street value of 1.2 million euros (£1m).
A further 120 kilos of cannabis worth 2.4m euros (£2m) was seized on Saturday in County Meath.
Two men were arrested during that Garda operation in Oldcastle.
COMMENT RULES: Comments that are judged to be defamatory, abusive or in bad taste are not acceptable and contributors who consistently fall below certain criteria will be permanently blacklisted. The moderator will not enter into debate with individual contributors and the moderator’s decision is final. It is Belfast Telegraph policy to close comments on court cases, tribunals and active legal investigations. We may also close comments on articles which are being targeted for abuse. Problems with commenting? email@example.com