UEFA will issue a two-season Champions League ban on Real Madrid, Barcelona and Juventus, unless they drop their European Super League plans and sign a settlement agreement, according to Sky Sports.
The European football governing body has already opened a disciplinary investigation against the three clubs.
The trio are the only clubs left of the initial 12 that were involved in the breakaway plans.
The nine clubs who pulled out, all signed the Club Commitment Declaration with UEFA on Friday.
UEFA is confident the three rebel clubs will be forced to sign up soon.
The prospect of disciplinary action appeared inevitable last Friday when a statement confirming the peace accord with nine of the clubs ended.
“UEFA has reserved all rights to take whatever action it deems appropriate against those clubs that have so far refused to renounce the so-called ‘Super League’.
“The matter will promptly be referred to the competent UEFA disciplinary bodies.”