A lawsuit claiming FDNY Commissioner Laura Kavanagh demoted people because of their age has a new defendant -- Deputy Mayor for Public Safety Phil Banks.

The lawsuit claims that Commissioner Kavanagh allegedly attempted to "replace them and other senior employees with younger personnel," and that Banks helped her do this.

The lawsuit was filed in March in the Brooklyn State Supreme Court by three former FDNY chiefs.

They are seeking back pay and the return of job titles for alleged age discrimination.