Malaysia Airlines says CEO Christoph Mueller will leave his job in September, way ahead of the end of his three-year contract, due to his "changing personal circumstances."

It says Mueller has expressed his interest to stay as a non-executive director. The airline said in a statement Tuesday that it has begun searching for a new CEO from a pool of internal and external candidates.

Mueller, a turnaround veteran, formally began his job in May last year to oversee a $1.56 billion overhaul that included cutting 6,000 jobs and axing unprofitable routes.

Mueller said "personal reasons will make it difficult for me to complete my full term," without elaborating. He said the airline is back on the right track for growth.