Liverpool legend Jamie Carragher labelled the Premier League giants "an embarrassment" for electing to join football's new Super League.
The Reds, last season's Premier League champions, are among six teams from England to have signed up for the new competition.
They will be joined by Manchester City, Manchester United, Chelsea, Arsenal and Tottenham, with Spain represented by Barcelona, Real Madrid and Atletico Madrid and Italy by Juventus, Milan and Inter.
Three further clubs are lined up to become founder members of a competition which could cast doubt on the future of the Champions League.
UEFA and the Premier League, LaLiga and Serie A have attacked the idea of the breakaway competition, along with the respective football associations of England, Spain and Italy.
Former Liverpool defender Carragher wrote on Twitter: "What an embarrassment we’ve become @LFC think of all the people who have come before us at this club who would be equally embarrassed as well. #SuperLeague."
FIFA said it could "only express its disapproval" at the move by the powerful clubs, who intend to carry on competing in their respective domestic leagues as well as playing in the Super League.
World football's governing body called for "calm, constructive and balanced dialogue" over the prospect of a split in the game. It was reported late on Sunday that the clubs involved have all left the European Club Association (ECA), which was previously chaired by Juventus president Andrea Agnelli.
Former England captain Gary Lineker suspects conversations will be held that result in less of a rupture than now appears apparent.
Shortly before the 12 clubs made their expected stance official, Lineker wrote: "Looking forward to the compromise with UEFA and the clubs....which, I sense, is what this is all been designed for. A power play."