Private equity group Charterhouse Capital has agreed to take a majority (65 per cent) stake in Environmental Resources Management (ERM) for around £585 million, in a deal that values the environmental consultancy at around  £618m ($1bn).

The group would buy a 65 per cent stake as part of a management buyout from rival private equity firm Bridgepoint. The remainder of the business, which includes the supermarket group Tesco as one of its clients in the UK, would be owned by the company's 440 partners, including the senior management team.

ERM chief executive John Alexander, while welcoming the deal, said: "We are pleased that Charterhouse shares our vision for the future growth of this company as we enter an exciting new stage of our development."

Alexander added that ERM had completed "an outstanding year", with $483 million in net revenues, up 12 per cent in year-on- year terms.

According to Charterhouse senior partner Stuart Simpson, the firm had followed ERM's progress for a number of years. He added that the company had grown to a size and leading market position that made this the ideal time for Charterhouse to make an investment in the significant growth potential of the world-class business.

ERM advises firms on their carbon footprints.

Structured as a management buyout from private equity peer Bridgepoint, Charterhouse will hold approximately 65 per cent of the firm, while ERM's partners will hold the remainder of the shares.