Bass' agents and the Amsterdam-based space travel company MirCorp released statements earlier today saying the singer was negotiating to travel on a Russian rocket in November.
MirCorp noted that the plan to fly to the International Space Station still required the approval of the Russian space agency Rosaviakosmos and its partners, the United States, Russia, Japan, Canada and Europe.
But a spokesman for Rosaviakosmos said that no such talks had taken place.
"It is as if I said I had bought Australia," Sergei Gorbunov told Reuters. "MirCorp has no right to sell these flights. They have no link to Rosaviakosmos, we have no contract linking us.
"[Bass' flight] is just an advertising stunt, I can promise you, " he added. "This is better advertising than he could ever pay for."
MirCorp was behind initial negotiations to send U.S. millionaire Dennis Tito into space for $20 million, but the deal was eventually brokered by the U.S. company Space Adventures.
Bass, who attended space camp near Titusville, Fla., when he was 12, said Thursday he was looking forward to completing this lifelong dream and was "completely overwhelmed."
According to MirCorp, the Los Angeles TV production company Destiny Productions, along with several corporations, offered to sponsor the 22-year-old singer's trek in the hopes of documenting it for a television special, Celebrity Mission: Lance Bass.
MirCorp said in a press release: "We look forward to working with the Russian Space Agency Rosaviakosmos to reach an agreement allowing Mr. Bass to realize his dream.
"MirCorp has fought for the past several years to open the exploration of space to all. We believe firmly that the excitement and beauty of this frontier should not be limited to a handful of professionals."
The company also claims to be in discussions with other candidates for the November mission. The earnings, they say, would help support the Russian cosmonauts' training center and mission control.