"Contamination of pig food with a hormone product has been identified in Belgium and the Belgian authorities have notified the authorities in Ireland," the EPA said.

"The source of the contamination has been traced to the Wyeth factory in Newbridge, County Kildare. The EPA has stopped the shipment of all wastes from the Wyeth site and has initiated an investigation into the situation," the statement added.

The waste water was shipped to a now-bankrupt Belgian reprocessing plant, Bioland, which is being investigated by Belgian prosecutors as a possible source of materials contaminated with the MPA hormone. Experts believe MPA can cause infertility in humans.

MPA, or medroxyprogesterone-acetate, is a growth hormone banned in the EU but is used legally in the United States, Australia and New Zealand. It also is a component of hormone replacement therapies for women in menopause.

It has been found in pig feed used on Dutch farms, prompting authorities in the world's third-largest pork-exporting country to start a criminal investigation and place restrictions on farms involved.

The scare is the latest to rock confidence in food supplies in Europe, where Britain's mad cow and foot-and-mouth disease woes, contamination of food with cancer-causing dioxins in Belgium and discoveries of beef proteins in chicken parts have all undermined consumer confidence.

The pig feed is suspected of containing material from Bioland, which reprocessed the waste sugar water from the Wyeth plant, where hormone pills are covered with a sugar coating.

Belgium's health food safety agency has said it found traces of MPA in materials Bioland supplied to two soft drinks firms, which bought in products from the bankrupt company.

Officials at the Wyeth plant were not immediately available for comment.

An Irish waste-recovery company, which sent the hormone-laced sugar water to Belgium for reprocessing, said it was cooperating fully with authorities.

Dublin-based Cara Environmental Technology Ltd, said through a spokesman it had "followed the letter of the law" regarding the shipments.

"Cara is cooperating fully," Kieran O'Byrne of Beattie Media in Dublin, spokesman for Cara, said.

Since 1999, Cara has shipped "a couple of hundred tonnes" of waste sugar water to Bioland, O'Byrne said. The water contains sugar left over from the process of coating pills.

From 2001, when Wyeth began coating a hormone therapy pill at the plant, the fluids contained traces of MPA, he said.

"To be honest with you, Wyeth and Cara followed the letter of the law down this whole thing. Everything has been done according to regulation," O'Byrne said.

Belgium's health minister and the head of Belgium's food safety agency have said Ireland did not property notify Belgium of the contents of the shipments.

The Irish EPA said its inspectors had checked records at Wyeth and at Cara, as well as county records regarding exporting of waste by Wyeth to other countries.

It said a report was being prepared and would be published when the investigation is completed.