American private equity firm Clayton, Dubilier & Rice made a winning £7.1bn auction bid for the British supermarket chain last year, following Morrisons’ initial agreement for a £6.3bn takeover by rival US firm, Fortress Investment Group.

But in January this year, the Competition and Markets Authority (CMA), opened an investigation into CD&R’s buyout of Britain’s fourth largest supermarket.

The US firm is the owner of the Motor Fuel Group (MFG) which is the largest independent operator of petrol stations in the UK.

In total, it runs 921 petrol stations across England, Scotland and Wales under brands including Esso, BP, Shell, Texaco, Jet and Murco.

Morrisons supermarket also operates 339 petrol stations across the UK and as part of the first phase of the CMA’s investigation, it said the deal “raises competition concerns in relation to the supply of petrol and diesel in 121 local areas across England, Scotland and Wales”.

These 121 areas have been highlighted as both MFG and Morrisons run fuel forecourts so would face “limited competition” after the merger, “meaning the deal could lead to an increase in prices”.

Colin Raftery, senior director of mergers at the CMA, said: “Prices for petrol and diesel have recently hit record highs, which makes it even more important that we don’t allow a lack of competition at the pump to make the situation worse.

“We’re concerned that this deal could lead to higher prices for motorists in some parts of the country. But if CD&R and Morrisons are able to address these concerns, then we won’t need to move on to an in-depth investigation of the merger.”

The CMA said CD&R has five working days to offer proposals to address these concerns after which the CMA would have five working days to consider whether to accept them or refer the deal for an in-depth phase two investigation.