No one at Ireland's Agriculture department, which has responsibility for animal experimentation, was immediately available for comment.

The term "experiment" in Ireland covers traditional substance testing on animals' skin or ingestion which leaves chemical, drug and cosmetic firms free from animal welfare standards on tests outside this definition, EU officials said.

EU rules also require tougher penalties on those who break animal testing laws than currently exist in Ireland.

Dublin did not respond to a first warning to bring its laws up to scratch, sent in March.

"I am disappointed that Ireland has not taken steps to bring its 19th century legislation fully into line with EU rules on animal experiments," EU Environment Commissioner Margot Wallstrom said in a statement.

Ireland now has two months to comply with a 2001 ruling from the European Court of Justice which ruled its animal welfare laws were insufficient. If not the Commission could ask the court to impose a daily fine, it said.

Wallstrom's spokeswoman Pia Ahrenkilde declined to comment on the size of the possible fine which would be decided at the last stages of the Court proceedings.

"It depends on many factors such as the seriousness of the damage caused and the country's gross domestic product (GDP)," Ahrenkilde said.

Two years ago the EU for the first time fined Greece 20,000 euros a day for illegally dumping toxic waste. Greece had to cough up a total of 5.4 million euros for breach of the 15-nation bloc's environmental rules.

One EU official estimated that Ireland's case would be seen as less serious.