Blatter: Brazil can stage World Cup in 12 cities
FIFA had initially wanted the tournament to be staged in 10 cities as it believed having fewer venues would make the logistics easier.
But after a meeting with Sao Paulo state governer Jose Serra, Blatter said FIFA would allow 12 cities.
"This country is not a country, it's a sub-continent, five-times world champions, and we are going to divide the Cup in 12 different cities," he told reporters.
Seventeen Brazilian cities have put themselves forward as candidates and a FIFA committee will begin a whirlwind one-week tour of them on Friday.
The candidates are Porto Alegre, Florianopolis, Curitiba, Rio de Janeiro, Belo Horizonte, Brasilia, Goiania, Campo Grande, Cuiaba, Rio Branco, Manaus, Belem, Salvador, Recife, Natal, Fortaleza and Sao Paulo.
Brazil was the only candidate to stage the 2014 World Cup, however there are concerns about the country's suitability as hosts because of transport and infrastructure problems and a soaring crime rate.
Serra said that he believed the opening match would be held in Sao Paulo while the final would be in Rio de Janeiro.
"I'm virtually certain that this will happen," he said.