The tournament is considered a dress-rehearsal for the World Cup that Brazil is hosting the following year at 12 stadiums which are being upgraded or rebuilt from scratch in Brazil's largest cities.
"At this pace, we are not going to have six stadiums ready for the Confederations Cup," he told reporters after visiting the 66,800-capacity Minerao stadium (pictured), home to Atletico Mineiro and Cruzeiro.
The Belo Horizonte stadium has more than 80 percent of its upgrade completed and is the closest to being ready, along with Fortaleza's Castelao stadium.
Recife's Arena Pernambuco is the main concern for the Confederation Cup organisers. Only 64 percent of the construction has been completed just eight months from the tournament, according to contractor Odebrecht Infraestructura.
Valcke was briefly declared a persona non grata by the Brazilian government in March for saying Brazil needed a "kick up the backside" to speed up preparations for the World Cup.
"We don't have a single stadium ready for the Confederations Cup. We have deadlines. Stadiums that are on schedule will host matches, those that don't make the deadline won't," Rebelo said.
The other venues chosen for the Confederations Cup are Salvador's Fonte Nova stadium, Rio de Janeiro's famous Maracana and Brasilia's Mane Garrincha stadium which is being totally rebuilt.
The Confederations Cup features FIFA's six regional champions along with the host nation and the World Cup holders.
Spain, Italy, Mexico, Uruguay, Japan and Tahiti have qualified for next year's tournament and will be joined by the winners of the Africa Cup of Nations.
