Three of the biggest player agencies in English football have threatened the Premier League with legal action if they press ahead with plans to introduce a controversial new salary cap.

CAA Base, CAA Stellar and Key Sports Management, who between them act for hundreds of players including Cole Palmer and Jack Grealish, instructed a leading London firm on Friday to write to the Premier League’s legal department. They complain that at no point has the Association of Football Agents been consulted on the issue and claim such a cap, known as anchoring, would be in breach of competition law.

Premier League clubs are expected to vote at a shareholders’ meeting on Friday on new financial proposals that include both squad cost ratio rules and anchoring, the latter of which would limit spending to five times the amount paid by the Premier League in prize money and broadcast revenue to the club which finishes bottom. Based on the 2023-24 season, when Sheffield United occupied 20th place and received £109.5 million, that would be £550 million.

The Professional Footballers’ Association has already threatened to launch legal action on behalf of its members and, as The Times revealed last week, is scheduled to hold a meeting with all 20 Premier League captains in the next few days because of the potential impact the changes could have on a club’s ability to match the salaries being paid by their top European rivals.

In the letter sent to Kevin Plumb and Jamie Herbert, the Premier League’s general counsel and head of governance, the agents have called for the proposed changes to financial regulations to be withdrawn. A failure to do this, they warn, will be met by their own legal challenge.

They argue in their letter that the implementation of both squad cost ratio and “top to bottom anchoring” rules would be in breach of section two of the Competition Act 1998 as well as an abuse of the Premier League’s dominant position, which they say would also be in breach of the same act. They also state it would be an unlawful restraint of trade, by artificially capping the amount clubs can spend on players, coaching staff, transfer fees and agents.

They claim there is no legal justification for these rules changes, rejecting the suggestion that the proposals are designed to maintain competitive balance in English football’s top flight.

The letter has also been sent to the Premier League’s legal advisory group and is sure to increase the pressure on the clubs to abort plans for the vote.

As The Times reported on Saturday, the clubs now voicing concerns about the proposals go beyond the original objectors at Manchester United and Manchester City, with some senior club insiders now questioning whether the voting will go ahead on Friday.

The Premier League has been approached for a comment but in a previous statement on this issue, a spokesperson said: “It is the League’s objective to maintain the Premier League’s value, competitive balance and ensure clubs operate in a financially sustainable way.

“We are engaging with our clubs, and they will continue to evaluate the proposals. They will have the opportunity to vote on them later this month.”