The Irish Recorded Music Association (IRMA) has taken legal action against mobile operators O2 and 3 Ireland.

IRMA's plenary summons against both companies is part of an effort to get Irish fixed line and mobile providers to introduce a graduated response system to tackle illegal file-sharing.

Last month the High Court of Ireland ruled that a three strikes system would be legal under data protection law. That allowed Internet Service Provider Eircom to go ahead and launch such an anti-piracy system.

It had agreed with IRMA, which represented the majors, to implement such a system. The two sides first clashed in court but an agreement was reached in early 2009.

This week Eircom introduced its system, targeted at the worst offenders. After three warnings, a copyright infringer would lose Internet access for a week. After a fourth, access would be cut for a year.

Unlike the U.K., New Zealand and France, Ireland has gone down this route without government legislation. Legal action and negotiation has brought a graduated response scheme into effect in a country whose recorded music trade value fell 26% to $73.8 million in 2009, according to the IFPI.

IRMA has said it is in negotiations with two other ISPs - reportedly Vodafone and Eircom's mobile subsidiary Meteor - to implement the same system.

Last month's court ruling made clear that IRMA and the labels should take legal action against other ISPs who fail to introduce the graduated response system. Clearly, Eircom would be at a competitive disadvantage if other telcos did not follow suit, voluntarily or not.

Other ISPs have not agreed to implement the anti-piracy measures. UPC, the cable TV operator and broadband provider, has a High Court hearing with IRMA set for June 17.