In a letter to the bosses of other teams, Karren Brady, vice-chairwoman of Premier League club West Ham, said EU membership helped players move easily to clubs in Britain because freedom of movement rules meant they did not need visas or special work permits.
Brady, one of the first women to have a senior role at a British club, is among several leading British business executives to support the 'in' campaign before a referendum on EU membership which could take place as early as June.
She is also a peer in Prime Minister David Cameron's Conservative Party.
Asking football chairmen to join the campaign to remain in the European Union, Brady said their clubs had benefited from membership by receiving funding to promote their sport and by being able to tempt players with cheaper flights and phone calls because of the bloc's single market.
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"Sitting on the side-lines cannot be an option in this referendum and I would urge you to speak up on the benefits for your club and the game in general," she said in the letter, published by the "Britain Stronger in Europe" campaign, of which she is a board member.
"Clubs and fans all benefit from European action, laws and funding. Leaving the EU would hurt our leagues, create uncertainty for European transfers, and be a step back for the next generation of footballers."
With Cameron seeking a deal to change Britain's relationship with the EU, both the 'in' and 'out' campaigns are stepping up their arguments before the referendum.
Opinion polls say that Britons are almost evenly split on remaining in the EU, suggesting thousands of still undecided voters will be decisive and both sides are keen to broaden the debate to beyond economic concerns.
(Reporting by Elizabeth Piper Editing by Jeremy Gaunt)
