When Morrison launched his Safeway bid in January he believed he would only have to sell 10 stores to satisfy competition concerns, but research from data and consultancy group CACI shows that Morrison and Safeway branches overlap in 78 cases.

The CACI study is based on a drive-time around stores of 15-20 minutes, leading experts to suggest that if Morrison is successful in his bid for Safeway he would have to sell on a large number of both Safeway and Morrison stores.

One expert commented: 'In order to satisfy the authorities he may have to sell almost a quarter of his store portfolio.' Rivals hope this factor will dissuade Morrison from bidding, although CACI researcher Patrick Tate comments that many of the other supermarkets face a similar overlap in terms of the drive-time factor.

Although Tate would not confirm the figures for rival bidders Tesco, Sainsbury's and Asda, industry experts predict this to be around 300 stores for Tesco, 250-300 for Sainsbury's and 250 for Asda.