Royal Mail is part of a swelling group of Britain's best-known companies in a legal battle against truckmakers in a £4bn price-fixing row.
The Road Haulage Association (RHA) announced in June it had secured no-win no-fee backing to launch action. It estimated 650,000 trucks bought by UK customers between 1997 and 2011 were subject to alleged price-fixing by major truck firms.
Royal Mail has one of the largest numbers of trucks in the UK, with a fleet of 49,000 vehicles. Sources told City A.M. the firm is part of a number of Britain's best-loved companies.
Last week, Sky News reported Greggs was in talks to join the action.
The legal case builds on a European Commission ruling that fined five truck manufacturers €3bn (£2.7bn).
The action led by RHA is seeking compensation from MAN, Volvo Group, Mercedes-Benz parent company Daimler, Iveco and DAF. It claims vehicles sold and leased back to them were done so at inflated prices by the so-called “cartel” of truck manufacturers.
Early indications suggest compensation could be in the region of £6,000 per lorry.
Royal Mail declined to comment.