The ban was attacked by Bolivia President Evo Morales, and Conmebol, the South American soccer confederation, asked FIFA to suspend the ban until the end of 2010 World Cup qualifying.
The countries affected were Bolivia and Ecuador. The Bolivian capital of La Paz (located 11,940 feet above sea level) and Ecuador's Quito (9,200 feet).
Morales, a big soccer fan, campaigned effectively to protest the ban. He played in a 15-minute soccer game with local mountaineers at Bolivia's highest Andean peak, Sajama, at an altitude of 19,700 feet, to show it was possible to play soccer at high altitudes.
"Let us reopen the discussion," Blatter told a press conference Tuesday in Sydney, Australia, site of the 2008 FIFA Congress.
Blatter opens to replace the altitude ban with a package regulating "football under extreme conditions" -- including heat, humidity and cold as well as pollution.