The European Club Association has set out potentially explosive plans to revamp the Champions League to include more matches and some form of promotion and relegation when the agreed format and football calendar concludes in 2024.

The ECA and Juventus chairman, Andrea Agnelli, spelled out the principles informing the top clubs’ push to reshape European football in a letter inviting all the ECA’s 232 clubs to discuss them at a special general assembly in Malta on 6 and 7 June.

Describing the proposals as “fundamental to the future of European football”, Agnelli set out a list including more European football to be played by clubs, a “pyramidal” structure across Europe, and more “mobility and dynamism across the system through carefully applied promotion and relegation”.

The proposals state participation will be based on “sporting meritocracy” not “historical privilege” – a response to reports that top clubs such as Juventus are looking for permanent membership of a Champions League elite competition.

ECA Representatives of the ECA declined to provide further detail, and said full proposals have not yet been worked out. Agnelli first set out his ideas for expanding the Champions League in an interview with the Guardian last year, suggesting top clubs could play more high-profile and lucrative European matches simply by switching the competition’s group stage from eight groups of four clubs to four groups of eight. He acknowledged that he foresaw an impact on national leagues, arguing they should reduce in size and the top clubs might field junior sides.

These early moves to develop such changes to European football’s sporting and financial landscape, which began on 19 March with an ECA and Uefa “brainstorming” meeting, have become politically fraught. Representatives of national leagues criticised reported ideas from that meeting – including playing Champions League matches at weekends, which Agnelli denied was a proposal – as a threat to the long-established structures.

In his letter to member clubs, Agnelli denounced that criticism as based on “incorrect speculation and rumour” and even urged ECA clubs not to attend a meeting of the collective body, the European Leagues, in Madrid on 6 and 7 May to which all ECA clubs have been invited.

In a scathing response, Lars-Christer Olsson, the European Leagues president, described Agnelli’s as “a strange letter” containing “false accusations” and said he expected clubs to be “grown up enough” to make their own judgment about whether to attend the meeting. He said he could see the leagues would have “different opinions” from the ECA proposals about the future, and that they plan to develop their own ideas for the post‑2024 formats with national leagues and football associations.

“Do not forget that it is the football associations that ‘own’ Uefa who take the final decision,” he said.

The Premier League issued a strong statement on behalf of its 20 clubs this month, emphasising opposition to any plans “that would alter the structures, calendar and competitiveness of the domestic game”. England’s top league also stressed that “the structures of domestic football are determined by leagues and their respective national associations”.