Several sources tell The Guardian and the AP news agency that talks are under way between Uefa and Concacaf, which include the World Cup host nations, the USA, Canada and Mexico.
An expansion of the Nations League would then take effect from the 2028/29 season.
The talks are seen as proof that Uefa wants to distance itself from the international football federation Fifa and seek other collaborations, without Fifa's involvement.
The Asian Football Confederation (AFC) is also said to have been involved in the talks, but the federation's ambition is to join the Nations League later.
Even if the tournament is expanded, it will not take up any more space in the competition calendar. The league phase will be played as planned during the national team break in the fall of 2028. The playoffs and final in March and June 2029, respectively.
The initiative comes in the wake of the storm of criticism that followed Gianni Infantino's plan to sell World Cup shares to private investors became public earlier this summer. Plans that he later withdrew.
UEFA President Aleksander Ceferin and his Concacaf counterpart Victor Montagliani have previously announced that they have lost confidence in FIFA and that Infantino should resign.
