Hundreds of jobs are to be created on the back of a new dairy production facility by leading food firm Glanbia.
The company is to build a new dairy plant in Belview, on the Kilkenny/Waterford border, which management said will be worth about 400 million euro to the economy.
Some 450 construction workers will be employed during the build.
Glanbia said the scale and scope of Belview is extremely ambitious and it will bring maximum return for local farmers and businesses as the dairy industry buys 90% of its raw materials from the domestic economy.
The company said it will employ 76 staff directly at the plant with another 1,676 jobs created indirectly on farms, suppliers and maintenance.
Taoiseach Enda Kenny attended the announcement in central Dublin. He said: "Glanbia is one of Ireland's great home-grown success stories and their investment in the south east region will be welcomed by rural communities and farmers.
"It is the largest single dairy investment in the history of the state and will contribute greatly to Ireland's export-led recovery."
Glanbia Ingredients Ireland Limited (GIIL) will fund the project with support from Enterprise Ireland, through the the Department of Jobs, Enterprise and Innovation.
The company is Ireland's leading dairy firm, processing 1.6 billion litres of milk, 30% of the country's milk pool, into a range of ingredients for more than 50 countries. All produce from the new facility will be destined for export.
Construction on the new factory will start on May 17 and it is expected to begin production in spring 2015. Glanbia said the facility will be capable of processing more than 700 million litres of milk and produce 100,000 tonnes of dairy powders a year.