British Members of Parliament have called for the Professional Footballers' Association to review the amount paid to chief executive Gordon Taylor after it emerged that he earned nearly £2.3 million last season.
Members of the Digital, Culture, Media & Sport select committee urged the review after PFA accounts showed Taylor had almost doubled his salary from the previous year.
Meanwhile, the players' union put just £100,000 into concussion and head injury research in the year ending last summer.
The Telegraph, which reported that Taylor is thought to be the world's highest-paid trade union chief, quoted Labour MP Ian Lucas as saying: "People have had enough of salaries at this level.
"At a time when, real wages in this country haven't increased since 2004, I think your average football supporter will be appalled. It's time that the PFA looked at the situation."
Conservative MP Julian Knight said the news of Taylor's salary "leads one to question the management at the PFA."
Graeme Le Saux, the former Chelsea defender who is now a member of the FA Inclusion Advisory Board, described the pay packet as "absolutely scandalous."
In October, Football Association chairman Greg Clarke told MPs the PFA had spent "millions" on Taylor's salary and "walked away" from footballers facing difficulties.
Taylor, who has been in charge of the PFA since 1981, responded by threatening to sue Clarke if he repeated the claim outside Parliament.