About 150 tillage farmers protested outside the Greencore premises in Athy, Co Kildare, this morning over the price they are being paid for malting barley.
The barley is used in the brewing and distilling industries.
The Irish Farmers' Association complains that while consumers are being asked to pay more for their beer, barley growers get less than 1% of the price of a pint.
It says that the remaining 99% goes to publicans, the Government, brewers and maltsters.
The farmers accuse Greencore Malt and Diageo of abusing their dominant position. They insist that market conditions justify a doubling of the current growers' premium from €15 to €30 a ton, raising the price from €140 to €160 a tonne.
The IFA Grain Chairman, Colum McDonnell, said Greencore Malt and Guinness are in a position to pass on increased costs to their customers and suppliers.
He said farmers do not have this option, so they must absorb the increased costs.
