To lose one regulatory case may be regarded as a misfortune; to lose two in less than six months begins to look like rather more than carelessness.

Unilever, the world's biggest ice-cream manufacturer, finds itself in just that position, however. On Wednesday the wholesaling practices of Wall's, its UK subsidiary, were condemned as anti-competitive after an investigation by the Monopolies and Mergers Commission said the company excluded rivals from access to retail outlets.

And only last March, the European Commission ruled that Unilever's Irish subsidiary HB had abused its dominant position in the Irish market by excluding rivals' ice creams from the freezer cabinets it supplies to shops. This decision, currently suspended pending appeal, stems from a complaint first made in 1991.

Mr Niall FitzGerald, chairman of Unilever's UK wing, describes such attacks by regulators as the price of success. And successful the Anglo-Dutch consumer group certainly is: it dominates most of Europe's big ice-cream markets and has well over half retail sales in Ireland and the UK. But competitors such as Mars, the US confectionery group, sense they are at last beginning to make headway with their complaints that the group's success is built on marketing practices designed to exclude them from the market.

It was the arrival of Mars on the European ice-cream scene that started the current round of investigations. It introduced its range of luxury ice-creams based on its best-selling confectionery lines. In the US, these had been highly successful. There, manufacturers do not control distribution and retailers have freezers displaying all the most popular brands.

The Snickers ice-cream bar was a best-seller within a year of its launch. In Europe, however, Mars found good brands were not enough. The existing manufacturers handled their own distribution, in some cases tying up outlets with exclusive contracts that forbade them from stocking rivals' products.

Following the 1991 complaint by Mars, outlet exclusivity was ruled illegal by the European Commission. But freezer exclusivity, the practice of giving retailers cabinets on condition they were not used for rivals' products, was not challenged until this year's decision banning it in Ireland.

The Monopolies and Mergers Commission had already banned outlet exclusivity in the UK in 1979. In 1994, it reported on freezer exclusivity, concluding it did not pose a sufficient threat to public interest to take action.

Wednesday's decision was on the use of independent dedicated distributors to deliver ice-cream to retailers. The MMC's ruling - endorsed by Ms Margaret Beckett, the outgoing trade secretary - was that it was anti-competitive. All wholesalers should be offered the same terms as the dedicated distributors, it concluded.

The real sting, however, was the commission's recommendation that a full review of the ice-cream industry was needed. During its investigation, concerns had been raised on various practices including freezer exclusivity. Unilever now faces its third MMC investigation in a decade.

"We are seeing a commercial battle waged by proxy. Mars is using the regulators to attack our competitive position - an approach not seen in Europe before but prevalent in the US," says Unilever's Mr Steve Williams.

Mr David Lang, of stockbroker Henderson Crosthwaite, sees the battle in similar terms: Unilever dominates because of the superiority of its ice-creams such as Magnum, Solero and Calippo. "Mars got stuck in early but lost the plot," he says. "They don't have the range and even where shops stock all the makes, Unilever has a preponderance of the top-selling brands."

A competition adviser who has been involved in earlier rounds of this battle says Mars shook up the sleepy European market when it introduced its premium ices. "But it was not Mars that reaped the benefits - it was Unilever which reaped them because of its stranglehold over distribution."

And another competition analyst says Unilever has recognised that to dominate a market needs control over only one part of the production process. "The market can support four or five manufacturers, but Unilever quickly realised its distribution system gave it an advantage which it is determined to defend."