Takuma Sato says that talks regarding a reserve driver role with Red Bull have fallen through.
The former Honda and Super Aguri racer had been a strong contender for Toro Rosso's second seat until the team decided to retain Sebastien Bourdais.
But subsequently Red Bull boss Dietrich Mateschitz revealed that Sato was being considered as a standby driver for both Red Bull Racing and Scuderia Toro Rosso, in case any of their drivers were sidelined.
However in a statement published on his personal website today, Sato ruled himself out of the Red Bull frame.
"I am no longer in negotiation with the Toro Rosso or Red Bull teams about their third driver positions," he said.
"I am very disappointed that we were not able to come to an agreement with them, but you never know what is around the corner."
Sato, who dropped out of the Formula One field when Super Aguri folded last May, remains determined to return to grand prix racing in the future.
"As everyone knows, I never give up, so we are still looking for the best options for the future," said the Japanese driver.