Ibaka, who was born in the Republic of the Congo, is still waiting to become nationalized by Spain before the championship begins on Aug. 31 in Lithuania.
"We hope he can play, even though we are not sure that he will be able to," Spain coach Sergio Scariolo said. "We are in the phase of waiting for the paperwork to go through."
Ibaka played for Spanish clubs for three years before moving to the NBA in 2009. According to Spanish media reports, he maintains a residence in Barcelona.
The preliminary list of 15 players, which will be reduced to 12 by the start of the tournament, also includes new Minnesota Timberwolves point guard Ricky Rubio.
Scariolo guided Spain to the continental crown in 2009, but the team finished sixth at the worlds last year.
Even so, Spain will be counted among the favorites.
The two finalists of the European championship automatically qualify for the 2012 Summer Olympic Games, while the third- through sixth-place finishers earn a spot in the pre-Olympic qualifying tournament.
The other players on Spain's preliminary roster are: Rudy Fernandez, Jose Calderon, Juan Carlos Navarro, Felipe Reyes, Fernando San Emeterio, Carlos Suarez, Xavi Rey, Victor Sada, Sergio Llull, Rafa Martinez and Victor Claver.