Liverpool would have to quit the Premier League in order to enter the controversial European Super League (ESL), according to one of the competition's existing rules.

Twelve elite clubs including the Reds woke up to a backlash this morning after it was confirmed they signed up for controversial proposals to join a 20-team breakaway.

It's a movement which has threatened the existence of football as we know it.

Bankrolled by US banking giant JP Morgan, the ESL is the brainchild of Real Madrid president Florentino Perez and American owners at three Premier League clubs - including Liverpool - who are one of 12 initial signatories for the much-maligned reform, which is set to come as a direct threat to the Champions League rather than the domestic system.

However, such has been the widespread condemnation against the proposals, the Premier League are amongst the game's existing governing bodies to have already threatened action.

Any clubs and players who go on to participate, should the ESL be rubber-stamped, would in turn be banned from several high-profile competitions - domestically, across Europe and internationally.

Liverpool and their contemporaries, meanwhile, would need permission from the Premier League to enter.

Based on the follow-up statement from officials in charge of the top division in England, that seems highly unlikely, while a decision would be judged by the Premier League board itself - and not a vote between the 20 clubs.

Quite significantly, there is already a rule in place which means that Liverpool, as well as fellow signatories such as Arsenal, Chelsea, Tottenham and the two Manchester clubs, would have to relinquish their Premier League place in order to pursue involvement with the ESL breakaway.

Premier League Rule L9 prevents movements such as the European Super League by stating that clubs are allowed only to enter certain competitions.

In full, the L9 guideline reads: Except with the prior written approval of the board, during the season a club shall not enter or play its senior men's first team in any competition other than:

L.9.1 - The UEFA Champions League;

L.9.2 - The UEFA Europa League;

L.9.3 - The FA Cup;

L.9.4 - The FA Community Shield;

L.9.5 - The Football League Cup; or

L.9.6 - Competitions sanctioned by the County Association of which it is a member.

As things stand, the 12 founder clubs are set to be joined by an further three initial members - while the remainder of the 20-team reform would be made up by clubs on account of their subsequent domestic success.

Response to the announcement, which came last night, has been almost universally damning.

Premier League chief Richard Masters has already written to the division's 20 clubs to make it abundantly clear the organisation will not support ESL reform in any way.

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According to Sky Sports, he said: "Premier League rules contain a commitment amongst clubs to remain within the football pyramid and forbid any clubs from entering competitions beyond those listed in Rule L9, without Premier League board permission. I cannot envisage any scenario where such permission would be granted."

Part of an official Premier League statement read: "The Premier League condemns any proposal that attacks the principles of open competition and sporting merit which are at the heart of the domestic and European football pyramid.

"We will work with fans, The FA, EFL, PFA and LMA, as well as other stakeholders, at home and abroad, to defend the integrity and future prospects of English football in the best interests of the game."