A FIFA proposal for a World Cup every two years and changes to the Club World Cup could cost the big domestic soccer leagues and UEFA around €8 billion ($9 billion) per season in lost TV rights and match day and commercial agreements, according to a report commissioned by the leagues.

More frequent international competitions, as well as additional international club games, could lead to major changes in the national leagues, including a reduction in the number of teams competing in them, a shift from weekend to weekday games, and fewer domestic games, the report said.

The report, compiled by consultancies KPMG and FTI's Delta Partners and seen ahead of publication by Reuters, predicted that in addition to cutting club revenue, such a move would hit viewer interest in games.