However, in an interview with MSN, Unkrich confirmed that the animated characters will return in a short feature that will screen before Cars 2 in 2011.
He said: "I really tried my best to end the story of Andy and his toys and bring that story to a close in a really nice way at the end of this film. That being said, we know that people love the characters, love Woody and Buzz, and would hate to say goodbye to them completely.
"I don't know that there would ever be a Toy Story 4. We don't have any plans for one - but we are trying to find ways to keep the characters alive. We have announced we're going to do a short film in front of Cars 2 that uses the Toy Story characters. We're going to keep them alive; they're not going away forever."
Toy Story 3 opens in the US today and will bow in the UK on July 19.
> Click here to read our review of 'Toy Story 3'