The South Korean Yonhap News Agency said Pak Ui-Chun is to spend Sunday through Wednesday in Moscow. The Korean Central News Agency, the North Korean government news service, reported he had left Pyongyang.
Pak, in an interview to the Russian Interfax News Agency, defended the North Korean nuclear program, using his country's official name, Democratic People's Republic of Korea.
"Recently the situation on the Korean Peninsula has been in quite a dangerous stage, while inter-Korean relations are worse than ever," Pak said. "The main reason behind this escalation is the United States' hostile policy in relation to the DPRK and the policy of confrontation with the North being pursued by the current ruling forces of South Korea."
North Korea denies sinking a South Korean naval vessel in March in spite of strong evidence of its involvement. In October, four people were killed when North Korea shelled a South Korean island.