Leeds United and Burnley want an independent commission to sit before the end of June to decide whether Everton have seriously breached the Premier League's financial regulations and potentially given the Goodison Park club an unfair advantage in their successful bid to avoid relegation, sources have told ESPN.

With either Leeds or Burnley set to be relegated from the Premier League on Sunday following Everton's 3-2 win at home to Crystal Palace on Thursday that ended Frank Lampard's team's relegation fears, the threat of legal action against the Premier League and Everton could place a question mark over the final relegation place this season.

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As reported by The Times, Leeds and Burnley submitted a joint letter to the Premier League on May 13 threatening to bring a claim for substantial damages against the league and Everton following the club's combined losses of £371.8 million over the last three years.

Sources have confirmed to ESPN that Leeds and Burnley also demanded details of what action, if any, has been taken by the Premier League to sanction Everton for their losses. The Premier League's profit and financial stability rules allow clubs to register losses of up to £105m over a three-year period or risk the prospect of financial penalties or, in serious cases, a points deduction.

Leeds and Burnley want an independent commission to sit and judge whether Everton's losses merit the club being sanctioned.

And sources have told ESPN that the two clubs stipulated to the Premier League that a commission should sit within six weeks of the submission of their joint letter in order to ensure that the matter is resolved before the start of the 2022-23 season in August.

Losses which can be attributed to the financial impact of the COVID-19 pandemic can be written off, but both Burnley and Leeds believe that Everton's losses potentially exceed those parameters.

Everton spent £33m on new signings in January and also recruited Manchester United's Donny van de Beek and Aston Villa's Anwar El Ghazi on loan. The transfer of defender Lucas Digne to Villa enabled Everton to recoup £27m of their January outlay.

Leeds and Burnley's challenge is the most significant involving the Premier League since West Ham were forced to pay £20m in compensation to Sheffield United in 2007 after breaching third party ownership rules to sign Argentina forward Carlos Tevez.

Sheffield United were relegated on the final day of the season due to West Ham, with whom they were level on 38 points, having a superior goal difference by just one goal.

Tevez scored seven goals in 10 games at the end of the season, including the winning goal in a 1-0 victory at Old Trafford against United on the final day of the campaign.