American consultant Tetra Tech has agreed a £636m deal to acquire RPS that trumped an earlier offer of £591m announced in August.

WSP has been mulling over a revised offer but confirmed today that it will not enter a bidding war.

The firm said: “WSP Global continues to value a disciplined approach to acquisitions to maximise shareholder value. With a strong balance sheet, WSP Global remains confident on its ability to capture opportunities and execute on its strategic ambitions.”

Tetra Tech is now set to be the new owner of RPS who employ consultants, designers, planners, engineers, and technical specialists across the world providing specialist services to government and private sector clients with a focus on front-end consulting.

RPS employs 5,000 people who will swell Tetra Tech’s overall staff numbers to 26,000.