The M25 scheme is expected to be released as a design, build, finance and operate (DFBO) contract in the Official Journalin November.
Vinci currently holds a similar contract on the Dartford Crossing, where Ringway and Cofiroute work with British firm Jacobs Babtie to operate and maintain the toll collection, traffic management and maintenance of the tunnels, roads and QEII Bridge.
The contract notice is expected to result in a bidding frenzy, with a host of European and American construction companies set to form joint ventures alongside their investment banks.
A source close to Vinci said: 'This contract will effectively cover everything: construction, operations, small capital projects, large capital projects and maintenance. The Highways Agency was hoping to award the deal in October, but it always takes longer to get these things moving with a project of this scale.'
US contractors Bechtel and Fluor are expected to join in the bidding war. In August the two companies emerged as front runners in the original £1.9 billion widening contract. Skanska is also believed to be working up a joint venture bid for the project.
Highways Agency finance director Mel Zuydam said: 'Procuring the M25 widening contract as a single DBFO has many advantages over multiple contracts. The ability to form a strategic partnership with one supplier will enable better value for money to the taxpayer, not just through leveraged economies of scale in procurement, but also through transfer of best practice between construction phases and the interfacing of the construction phases to minimise congestion.'