A senior official at Japan's foreign ministry has held separate phone talks with US and South Korean counterparts over North Korea's repeated launches of ballistic missiles.

Funakoshi Takehiro, who heads the Japanese Foreign Ministry's Asian and Oceanian Affairs Bureau, spoke by phone with the US Special Representative for North Korea, Sung Kim, on Sunday morning. Funakoshi also talked with South Korea's Special Representative for Korean Peninsula Peace and Security Affairs, Kim Gunn.

The officials agreed that the frequent ballistic missile launches by North Korea since late last month, including one in the early hours of Sunday, pose a pressing threat to regional security and a serious challenge to the international community.

They also exchanged opinions on Pyongyang's sharp reaction to a critical remark by the International Civil Aviation Organization. The UN body said the North's launches are a danger to civil aviation.

The officials confirmed that the three countries will continue to work closely together to strengthen deterrence in the region and to achieve the complete denuclearization of North Korea.