BEIJING, July 23 — China has expanded its zero tariff policy to cover 63 countries, marking another step in its broader strategy to deepen trade ties and promote higher-level economic openness, according to the country's top customs authority. The announcement follows Beijing's decision in May to extend zero tariff treatment to imports from all 53 African countries with which China maintains diplomatic relations. To support the expanded policy, Chinese customs authorities have introduced a range of facilitation measures. Looking ahead, the General Administration of Customs said it will continue implementing high standard opening up measures and trade agreements. The agency also plans to improve coordination in customs procedures, quarantine standards, and rules of origin to facilitate smoother international trade flows.