Masterfoods is to seek what is likely to be millions of euro in damages from Unilever after a lengthy legal battle between the two major consumer goods firms was returned to the High Court in Dublin within the past two weeks.

The high-profile action, one of the longest-running in the State, has been closely watched by retailers around Europe.

It was initiated in 1990, when Masterfoods, a subsidiary of Mars, sought to prevent HB, which is owned by Unilever, from forcing retailers to only stock HB-branded products in freezers supplied free of charge or at a nominal rent by HB to stores. Masterfoods claimed HB's position was in contravention of European competition rules.

However, the High Court ruled in favour of HB and Masterfoods appealed the case to the Supreme Court. It also lodged the case with the European Commission. The appeal to the Supreme Court was stayed pending the outcome of rulings from Europe, which have ended with the case returning here.

The Supreme Court has now instructed the case to be returned to the presiding competition judge in the High Court, Mr Justice Liam McKechnie, to assess damages that could be due to Masterfoods.

The Mars subsidiary has yet to determine the amount of damages it believes it is entitled to, but it is certain to be very substantial. However, an assessment of the claim is likely to be highly complex, as Masterfoods and the High Court will have to examine the extent to which the company's sales were adversely affected by the practice of freezer exclusivity.

Ireland's ice-cream market is believed to be worth more than €120 million per annum, with HB retaining a majority share.