BBDO, D'Arcy and Saatchi & Saatchi have pitched for the brief and a decision on an agency is expected soon.
Leo Burnett Greater China chief executive officer, Dennis Wong, said the decision to resign the mobile telco account was made after detailed consideration.
"We believe the decision will bring mutual benefit to both parties," Wong said.
"We are no longer the agency for SmarTone, but we are still helping the brand finish all the existing work before we go."
