A group of around 150 Greene King (GK) tenants are being asked to pledge financial support to keep their challenge over beer prices alive.
Solicitor Maitland Walker, which is handling the case, is writing to around 600-700 of the pub company's tenants and asking them to commit to a small monthly fee to fund the case.
If successful an official complaint to the Office for Fair Trading will be presented within the next couple of months accusing it of abusing its dominant position.
The challenge is being headed up by former Greene King tenant Meeko Oates. He claims support from tenants in the Cambridge, Oxfordshire and Bury St Edmunds areas.
Greene King has been accused of ripping its tenants off over beer prices by supplying managed houses the same beer for considerably less, a claim it categorically denies.
Priors Inn Landlord Geordie Howgate, a Greene King tenant of 10 years, is quitting in July in protest at what he believes is now an uneven playing field.
Howgate said: "I found a distribution company in Kent that could supply me a 36-gallon barrel of Greene King IPA for £78.96 less than the brewery. This is absolutely ridiculous, but people won't stand up and be counted because they are afraid of what Greene King might do."
However, in a statement released in May, David Elliott, managing director of the leased and tenanted division of Greene King - Pub Partners, said: "Pub Partners' strategy is to provide the best tenants a low-cost entry into the pub industry and to ensure that both they and Greene King make a reasonable profit."
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