North Korean leader Kim Jong Un's right-hand man and one of the top officials involved in nuclear talks with the United States, Kim Yong Chol, has been replaced as chief of a key espionage agency handling inter-Korean affairs, a report said Wednesday.

Kim Yong Chol, head of the United Front Department, was recently replaced by Jang Kum Chol, South Korea's Yonhap news agency reported, citing an official with the country's parliamentary intelligence committee.

The official did not state a reason for the dismissal. The Japan Times could not immediately confirm the report, but Kim Yong Chol was notably absent from Kim Jong Un's entourage that arrived in the Russian Far East city of Vladivostok on Wednesday for a summit with President Vladimir Putin, according to images and video of the leader's departure and arrival.