Infantino told a news conference the Qataris were open to the larger format. FIFA would make a decision no later than June, once a feasibility study is over, he said.
Saudi Arabia, the United Arab Emirates, Bahrain and Egypt launched a diplomatic and trade boycott of Qatar in June 2017 that has complicated the prospect of sharing the tournament.
The countries accuse Qatar of supporting terrorism, which it denies.
"We are doing football not politics," Infantino said.
FIFA voted in 2017 to increase the size of the tournament to 48 teams starting from 2026 but, since then, Infantino has been considering the possibility of bringing the change forward to 2022.
"Most football association across the globe hope for opening up the World Cup to more teams," he said, lamenting that continental champions such as Cameroon, Chile and the United States were absent from last year's World Cup after failing to qualify.
"If it is possible to organise a 48-team World Cup in Qatar with some games in neighbouring countries, that will be great," he said.
Infantino said it was "premature" to speak of a planned joint bid from Spain, Portugal and Morocco for the 2030 World Cup, which would be the first time countries from different continents had applied to stage the tournament.
"I welcome all bids. The more the better," he said.
Infantino was speaking following a FIFA executive summit in Marrakech which brought together some 60 football associations.
(Editing by Peter Graff)
