Bechtel has launched a legal challenge against HS2 after losing out on the £1bn contract to build Old Oak Common station in west London.
Last month a Balfour Beatty and Vinci consortium was named construction partner to deliver the station, beating rival bidders BAM Nuttall/Ferrovial Agroman (UK), Bechtel, and Mace/Dragados.
Now Bechtel has lodged a claim with the Technology & Construction Court, according to a report in Sunday Times, over the handling of the procurement process.
The firm is understood to be unhappy about the scoring of its bid after receiving feedback from HS2 in a 200-page document.
Bechtel pulled out the bidding last year for the Euston Station terminal to focus its efforts on Old Oak Common.
The firm is working with HS2 already as development partner for the second phase of the high speed rail line.
It took over the £170m role initially awarded to CH2M, two years ago after third placed losing bidder Mace threatened legal action over that contract award.
Fellow US consultant CH2M withdrew after Mace raised concerns about possible conflicts of interest after HS2 appointed CH2M European managing director Mark Thurston as its new chief executive
Both HS2 and Bechtel would not comment on legal matters.