The government could block plans by the Issa brothers to merge their businesses into a £12bn retail empire.
The Blackburn-based brothers are planning to merge their forecourts business with Asda, which they took control of in 2021 in a £6.8bn deal back by TDR Capital.
A combination of Asda and EG Group in the UK would create a sprawling group with 581 supermarkets, 700 petrol forecourts and more than 100 convenience stores.