South Korea's nuclear envoy on Thursday says now to September is a critical period in which to resume denuclearization talks with North Korea.

Lee Do-hoon, special representative for Korean Peninsula peace and security affairs, made the remark while speaking to reporters during a four-day trip to Washington.

Lee said positive developments, such as the ongoing Beijing-Pyongyang summit as well as correspondence dispatched from North Korean leader Kim Jong-un to the U.S. and South Korea, respectively, bode well for the prospects of resuming denuclearization dialogue.

Such talks have been deadlocked since the breakdown of the Hanoi summit in February.

The nuclear envoy added that South Korea and the U.S. plan to actively engage in diplomatic activities and will include other countries such as China and Russia in these efforts.

Lee said in a speech the previous day at a Washington-based think tank that North Korea should respond to President Moon Jae-in's outstanding invitation to hold an inter-Korean summit before the South Korea-U.S. summit next week.

[Photo : YONHAP News]