The directive drew fire from some of Musgrave's 2,100 British franchisees last week, who claimed the demand could force some of them out of business. Already under pressure from the sweeping expansion of groups such as Tesco, smaller retailers have been left reeling as competition in the sector has intensified.

Cork-based Musgrave, which owns the Budgens chain in Britain as well as Centra and Supervalu in Ireland, attempted to defuse the situation last week by saying that only a small proportion of British Londis franchisees will be hit by the move.

In a statement issued to the Sunday Tribune last week, Musgrave said it is the first time in 10 years that membership conditions have been changed.

It added that "very few retailers" within the group will be affected "as the vast majority are already ordering in excess if this new threshold".

It claimed that, following discussions with retailers who have joined Musgrave from other symbol groups, the £3,000 a week minimum order is "still significantly less than many of our symbol sector competitors. We have one of the most competitive offers in the marketplace".

The British Competition Authority has just published an interim report on the supermarket sector, which is under investigation amid claims that smaller retailers are being forced out of business due to the dominance of players such as Tesco.

More pressure is being piled on by firms such as Asda, owned by US giant Wal-Mart.

It is opening more convenience stores in Britain to combat falling sales at its traditional outlets.