Clubs in eastern Europe are "buying'' where they finish in the league and the extent of match-fixing is far greater than previously thought, the head of the international players' union FIFPro has claimed.
FIFPro general secretary Theo van Seggelen said players had told him the practice is widespread in Croatia, Serbia and other countries.
Van Seggelen told insideworldfootball: "In certain countries in eastern Europe, clubs are buying their position in their competition.
"They know in advance who will be one, two, three, four and five etc. They deal with each other. I heard it from the players. It happens in Serbia, it happens in Croatia, and other countries.
"They basically make their own agenda. It's been going on for some time. There is going to be a huge case in a couple of months and a lot of arrests but I can't say more.''
The problem of match-fixing has been thrust into the limelight after a major corruption scandal in Turkey which has seen 93 suspects indicted and Fenerbahce banned from the Champions League.
Van Seggelen said match-fixing could explain why so many players go from eastern Europe to western leagues but fail to make the grade.
He added: "I have often wondered why, when you look at young players from certain eastern European countries going to western Europe for a lot of money, suddenly they are not as good as everyone thought they were.
"Maybe the answer is that they organise scoring 25 goals per season in their own league. You have to realise how big a problem this is. It's been going on for maybe the last 10 years.''
UEFA said Van Seggelen had not raised his claims with them but had made tackling match-fixing a priority. UEFA's betting fraud detection system monitors more than 29,000 domestic and 1,800 UEFA matches each season.
UEFA head of communications Rob Faulkner said: "Any betting irregularities or suspicious matches that are brought to our attention will be investigated through our network of integrity officers and by passing all information on to the relevant national authorities.''