Miners who have been on strike at Tara Mines Ltd since last weekend have escalated their action, stopping consignments by rail from the mine in Co Meath to Dublin Port.
Tara Mines ships 400,000 tonnes of zinc concentrates to its European smelter customers each year. The SIPTU members yesterday placed a picket at the railway link to the mine which is normally used to bring up to four daily shipments to Dublin.
Talks broke down after 22 hours last week. The dispute centres on the miners' claim that Tara broke an agreement on the deadline for training workers as full-time miners. The miners have continued to complain about the employment of Canadian and Norwegian contract workers.
The regional secretary of SIPTU, Mr Mike Jennings, said the union was trying to revive contacts with the company and the Labour Relations Commission. Tara Mines has warned that it will have to issue protective notice to the other 440 workers.