Both operate substantial businesses in the UK and the deal, which is expected to be completed leter this year, would create a major energy services operation employing over 16,000 staff.

The investigation is at a preliminary stage where the CMA is calling for comments from the interested industry companies as to whether the merger would see a substantial lessening of competition within any market or markets in the UK.

Firms have until 7 June to submit any comments to the CMA for a decision to be taken by July 19.

In the UK and Ireland, the rebranded Equans business – formerly Engie Services – is presently the larger of the two operations enjoying revenue of over £2bn.

Equans’ activities cover a host of areas from technical services, facilities management, construction and regeneration and renewables, employing 13,500 staff  – a significant part of the overall new global operation.

In the UK, the former Engie Regeneration, which originally came from the former Keepmoat business,  turned over £623m in 2020, but booked significant losses of £77m blaming the pandemic and discontinued businesses. The firm employs 2,800 staff.

Bouygues E&S Solutions is a smaller UK operation employing around 2,700 staff with revenue of £250m.

The Equans operations would be combined with Bouygues’ Energy and Services (E&S) division.