A meeting of the Association of Southeast Asian Nations (ASEAN) opens on April 3 under tight security in the Cambodian capital.
Reforms in Myanmar, North Korea's rocket launch plan, and maritime disputes are expected to top the agenda at the two-day meeting in Phnom Penh.
The Philippines and Vietnam have accused China of flexing its military muscle over the disputed South China Sea.
China has rejected "internationalization" of the dispute over the resource-rich maritime area, preferring to discuss it bilaterally or with ASEAN, which operates on a principle of consensus.
Based on reporting by Reuters and AFP