The SEC Network, an American digital cable and satellite channel, has banned advertising from fantasy sports providers FanDuel and DraftKings.
The ban has been imposed because of the apparent difficulty in determining whether sports betting should be constituted as gambling.
SEC commissioner Greg Sankey said: “Is it a form of gambling? Is it a form of skill game? I think there is some question about that.”
Daily fantasy sites have long existed outside US laws prohibiting sports gambling because they have been classified as games of skill rather than chance.
