Initiatives mooted yesterday to strengthen the Competition Authority have long been a feature of the "war" against cartels in the US. The authorities there have the support of the FBI when pursuing such groups - and conspirators who expose price-fixing can secure immunity from prosecution.

The evidence was available to the Director of Public Prosecutions, Mr Jim Hamilton, who said he was "quite convinced" of the merits of immunity programmes. The Attorney General, Mr Michael McDowell, said it would be "entirely self-deluding" to suggest the authority could secure prosecutions without the Garda.

Mr James Griffin knows these arguments more than most. As deputy assistant attorney general at the US department of justice, he heads its powerful anti-trust division.

Whereas the Competition Authority in the Republic has been blighted by poor resources and departing staff, competition is big news in the US. A lengthy investigation into the vitamin business, led by Mr Griffin, resulted in fines last year of almost $1 billion (€1.17 billion).

"We believe that a predictable, clear, transparent leniency policy results in the successful prosecution of cartels, some of which might never have been successfully prosecuted," he said. "I think cartels are among the most difficult criminal cases to investigate and prosecute. The reason is that they are conspiracy crimes and there's no clear, outward, identifiable action by conspiracies that signals a crime."

Cartels are estimated by the Competition Authority to cost Irish consumers about £500 million each year. Mr Griffin said they operated in three manners: price-fixing; bid-rigging; and in the allocation of market share.

"They know that they're involved in criminal conspiracies. We have seen them take elaborate measures to ensure that they don't get caught either by their customers or by law enforcement officials."