Sebastien Bourdais was released by the F1 team
Sebastien Bourdais is threatening legal action against the Toro Rosso team, who sacked him following a string of poor results in this year's championship.
Bourdais has scored only six points in 27 grands prix for Toro Rosso.
But he said: "I consider that Toro Rosso has breached contractual duties. Nothing in my behaviour would legitimise a decision to terminate.
"I have instructed my lawyers to review the situation including the possibility of issuing legal proceedings."
Bourdais' place in the Hungarian Grand Prix on 26 July is expected to go to Spain's Jaime Alguersuari, who, at 19, would become the youngest ever Formula One driver.
Bourdais added: "I am even more frustrated by the team's decision considering that the latter has been taken immediately before the Hungarian Grand Prix, where a new highly-competitive racing package will be introduced in order to try and overcome current difficulties.
"I am convinced that if I was given the chance to race with such a new package I would have had the opportunity to achieve satisfactory results."