However, he suggested that 16 of those teams would go home after just one knockout match, and the remainder of the tournament would be played, as now, with a 32-team group stage, followed by a knockout phase.
Infantino, speaking during an event at Bogota's Sergio Arboleda university, said a final decision would be taken by the FIFA Council in January, Colombian media reported. A FIFA spokesperson confirmed that the reports were accurate.
"These are ideas to find the best solution, we will debate them this month and we will decide everything by 2017," Infantino was quoted as saying. "They are ideas which we put forward to see which one is the best."
Infantino said his suggestion was to have a preliminary knockout round involving 32 teams played in the host country, with the 16 winners reaching the group stage. A further 16 seeded teams would get a bye into the group stage, he said.
"The idea is that 16 teams would qualify directly to the group stage and the other 32 would play in a preliminary phase, in the country where the World Cup is being played - they would play for the remaining 16 places," he said.
"It means we continue with a normal World Cup for 32 teams, but 48 teams go to the party.
"FIFA's idea is to develop football in the whole world, and the World Cup is the biggest event there is," he added. "It's more than a competition, it's a social event."
Infantino was elected FIFA chief on Feb. 26 to replace Sepp Blatter, who received a six-year ban for ethics violations.
A key point of Infantino's election platform was to increase the tournament to 40 teams, although critics say this number creates difficulties in finding a suitable and simple format.
Germany coach Joachim Loew said on Sunday that a larger tournament would "dilute" its sporting value, while European clubs have strongly opposed an increase in the number of teams.
(Writing by Brian Homewood in Berne; Editing by Ken Ferris)
