The following article provides key strategies for responding to one of the most frequently asked interviewer questions "Why did you leave (or seeking to leave) your company?"
Be Succinct
Describe the reason for your departure directly and succinctly. Do not go into great details unless they ask you for the details. The longer you speak on the subject the more suspicious the interviewer will become. For example: When first asked why he left his former company Bart could succinctly state "My company merged with another firm and the new management wanted to bring in their own team. Prior to the merger I was a strong performer with positive performance reviews."
Provide References
You could then say that you will be happy to provide references from a former colleague and boss to verify your performance. Demonstrating a confidence and willingness to provide references to support your reasons for leaving is a powerful way to ensure you are believed.