Sainsbury boss Sir Peter Davis is reported to be willing to work with a rival supermarket chain on a joint bid for Safeway.
The Guardian said Sir Peter has also ruled out launching an indicative counterbid for Safeway if entrepreneur Philip Green decides to make an offer.
He added that the battle for Safeway was a “defining moment for the grocery business” and that all would-be bidders needed clarity from the competition commission on how many stores they would be forced to sell to win approval and who would be allowed to buy them.
Sir Peter told the paper that there would be “no single winner” for the Safeway estate and that “we would be very happy to talk to other parties when we know what might be possible”.
Sir Peter revealed he was devoting 25% of his time, “mostly Saturdays and half of Sundays”, to the bid effort.