The director of a diamond mining company has admitted to possession of €29m worth of cocaine.

Gareth Hopkins, 33, pleaded guilty to possession of the drug for sale or supply at Ballycoolin, West Dublin and at Beech, Leixlip, Co Kildare on 26 June, 2012.

About 400kg of cocaine were seized during a joint operation by gardaí and customs officers.

Dublin Circuit Criminal Court previously heard Hopkins, with addresses at Carnlough Road, Cabra and Leixlip, was director of a recycling company, a diamond mining company in Sierra Leone and had interests in a Polish tobacco company.

Gardaí had claimed in the District Court that he was involved in the large-scale importing of cocaine from South America, which was shipped to Ireland hidden inside lengths of timber.

They also alleged Hopkins was responsible for the storage and distribution of the drug, as well as extracting the cocaine from the wood.

Mary Ellen Ring remanded Hopkins in custody until sentencing in May.