MotoGP could expand to 22 races after 2021 with a rotational system catering for a potential five rounds in Spain and Portugal, according to series boss Carmelo Ezpeleta.
Spain already has four races - Barcelona's Circuit de Catalunya, Jerez, Valencia and Motorland Aragon - on a 19-round calendar but Portugal's Portimao circuit is interested in joining them.
Finland is set to join next year and Indonesia the season after.
Ezpeleta, chief executive of the commercial rights holders Dorna, told the MotoGP.com website that one region could not host a quarter of the races.
"We can do it another way, like a tender and say who is paying more and do that, but we will not do that. We will first talk to the people to see if they are interested or not to continue with this situation," he added.