US engineering consultancy CH2M Hill has approached UK engineer Atkins about a possible £3bn merger.
Over the weekend The Times reported that CH2M made a senior level approach at the end of last year to explore whether a tie-up could work, however it is unclear how far talks developed.
The two companies have worked together in the last few years on major UK infrastructure works, including the London Olympic Games, as delivery partner on HS2 phase one and early design for Crossrail 2.
CH2M expanded in the UK back in 2011 when it acquired another engineering consultant, Halcrow.
The US firm is the largest of the two businesses, employing about 25,000 employees in more than 50 countries, with around £4.3bn revenue. Atkins has more than 18,000 employees and generates about £1.9bn in turnover.
Both engineering groups have a global reach with Atkins also said to be keen to expand in the US market.
