UEFA president Michel Platini has defended a ban on third-party ownership in football - calling it a form of "slavery".

One of the most famous agents in the sport, Jorge Mendes, who has Cristiano Ronaldo and Jose Mourinho as clients, claims the ban is illegal.

Platini said: "I have put a lot of pressure on FIFA to stop third-party ownership ... it is shameful; we're dealing with a type of slavery that belongs to the past."

Ironic, Platini labeling 3rd party ownership as "slavery" yet fully behind a Qatar world cup with stadiums built by involuntary servitude...

— Second Yellow Card (@SecondYellowCrd) March 16, 2015

Third-party ownership is common in several countries, where companies own the economic rights of players and benefit from their transfer fees.

It has been illegal in the Premier League since 2008.