Offering clubs a qualifying place based on past performance in a new-look Champions League format would create a "de facto closed league", according to European Leagues president Lars-Christer Olsson.
European Leagues, which represents 37 domestic leagues across 30 countries, called together its members to a virtual meeting last Friday to present UEFA's proposals for the shape of European club competition from 2024 onwards.
It raised concerns over UEFA's plans to offer a safety net to clubs who miss out on conventional qualification, with two extra places available to countries with automatic group-stage qualifying based on their co-efficient ranking, calculated on historic performance.
A third place is understood to be available based on co-efficient ranking for countries without an automatic group-stage place.
The changes are widely viewed as an attempt by UEFA to appease Europe's heavyweight clubs and ward off the threat of a Super League.
A European Leagues statement issued on Friday referred to the "possible impact of access" to the competition and Olsson, a former UEFA chief executive, told The Times: "For me, it's a principle that the historic coefficient should not be part of an international competition at all.
"We will have a de facto closed Champions League."
UEFA's proposals could mean as many as six teams qualifying from a single league, such as the English Premier League, in future.
In addition to the three extra co-efficient places, France is understood to be being offered a fourth automatic position in an expanded 36-team group phase.
The teams would play in one league playing 10 matches each in a so-called 'Swiss system'.
European Leagues has expressed "strong concerns" about the calendar impact of the extra games, which would take the competition from 125 to 225 matches.
It is understood the leagues' view is that eight matches in the Swiss model - still an increase of two on the current group phase - was the most that could be accommodated in the current domestic calendar. Teams finishing between ninth and 24th would also play extra matches in order to play off for a place in the last 16.
UEFA is presenting the proposals to the 55 national associations on Tuesday.