Olsson told the Financial Times: "Too many clubs plan as if they are playing in Europe even though not that many actually qualify. We are determined to be firm about this system.
"In future, clubs will not be allowed to have significant debts to players or any related party.
"What has happened in many cases until now is that too many clubs have been indulging in, if you like, financial doping, recruiting players but not paying their debts, and sometimes not paying salaries. Now, they will have to prove they have sound finances to play in our competitions.
"We can ask an external auditor to intervene if we are suspicious that a club is not fulfilling the requirements. After that, we have the authority to expel clubs from our competitions.
"It's very serious but we will not make any compromises because it is essential to protect the credibility of the professional game.
"If the information I have read is correct, Leeds would be an example of a current club that would not be allowed to play in Europe. It may well be that some clubs won't get a license for next season."