A court in Drogheda has convicted six farmers, including senior members of the Irish Farmers Association, of breaching the Competition Act 2000.
The men were fined sums totalling €20,000.
The prosecutions were taken by the Competition Authority following a protest at Drogheda Port two years ago when a grain-carrying ship, the Dutch registered vessel the M.V. Arklow, was unable to offload its cargo due to the number of protesters at the port on August 31st 2002.
The protesters were demonstrating against the importation of non-EU grain into the country.
The convicted men include the vice-president of the IFA, Mr Ruaidhri Deasy, IFA grain committee secretary and chairman, Mr Fintan Conway and Mr Paddy Harrington and the former chair of the IFA in Louth, Mr Raymond O'Malley
Also before the court were farmers Mr Colm McDonnell, Ardee and Mr George O'Brien, Tullyallen of Drogheda.
They were convicted of reaching an agreement with the objective of distorting competition in the wheat trade at Drogheda Port on August 31st, 2002.
Judge Flann Brennan acquitted them of charges alleging they had distorted competition in the wheat trade.
The farmers have confirmed they will appeal the conviction.