The Issa brothers are reportedly considering merging Asda and EG Group in a deal that would create a retail giant worth more than £10bn.
The combination would create a group with 581 supermarkets, 700 petrol forecourts, and more than 100 convenience stores in a bid to refinance the current debt.
The merger talks have prompted fresh calls from GMB to expand the powers of the Competition and Markets Authority (CMA).
Nadine Houghton, GMB National Officer, said: “This merger isn’t in the interests of the 200,000 impacted workers, or the UK economy, or even consumers. It simply suits the debt refinancing arrangements of a private equity firm and their business partners.
“GMB stands on the side of hard-working families in calling for the role of the CMA to be expanded – giving greater regulatory oversight in relation to private equity buyouts and ensuring greater protection of both consumers and workers.”