SPFL chief Neil Doncaster has attacked "sinister" plans by some of Europe's top clubs to change the format of the Champions League.
Clubs in Europe's top leagues are said to be pushing for changes which would see them guaranteed Champions League football regardless of league position.
"I think this is a very sinister development," Doncaster told Radio 5 Live.
"For football fans around the world we should be very concerned about this."
Karl-Heinz Rummenigge, who heads up the European Clubs' Association, has proposed "a tournament consisting of 20 teams from Italy, England, Spain, Germany and France".
It has been suggested that the likes of Real Madrid, Barcelona, Juventus, Bayern Munich, Manchester United and Chelsea should be guaranteed entry to the Champions League, regardless of their league position.
This has led to fears that clubs outside Europe's top five leagues, such as Celtic, Porto and Ajax, will be left with little hope of qualification for Europe's premier club competition.
"What we're seeing now though, quite worryingly, is that there are moves within the movers and shakers of European football to try to re-shape the Champions League, potentially remove the champion's route and make it harder, perhaps impossible, for the champion clubs of smaller nations to participate in the Champions League," Doncaster explained.
"I think this is a very sinister development. The likes of Celtic, Rangers, Aberdeen, Ajax, Porto, these are huge brand names, huge clubs with great histories and great global fan bases. And there's the possibility that some may try and limit or remove their access to the Champions League.
"So, I think, for football fans around the world, we should be very concerned about this and do what we can to ensure that the biggest clubs from all leagues retain that access to the Champions League and we don't let the very biggest clubs in the biggest nations bully the rest of European football."
Doncaster accepts that the financial gulf between Europe's top leagues and those operating in the likes of the Scottish league is unlikely to be reduced, but argues that champions from smaller countries still deserve a crack at the Champions League.
"The financial disparity is huge. It's always going to be very difficult for the bigger clubs in smaller nations to compete on the same playing field with the bigger clubs in the biggest nations. But let's remember it's only a couple of years ago that Celtic were beating Barcelona at Celtic Park.
"What's important is that clubs are given the opportunity to have a go. In a one-off game anything can happen.
"What's vital for the health of the European game is that we protect that champions route.
"The big financial disparity is worrying but we need to do what we can to try to redress that balance and to protect these big clubs in their own communities and try to limit the huge power of the very biggest clubs who seem to be dominating the agenda."