South Korea's top nuclear envoy departed for Moscow on Tuesday for talks over the Democratic People's Republic of Korea (DPRK)'s nuclear issue, the foreign ministry said Tuesday.

Cho Tae-yong, who represents South Korea at six-party talks aimed at dismantling the DPRK's nuclear program, will meet with his Russian counterpart Igor Vladimirovich Morgulov and other officials during his three-day trip to Moscow through Thursday.

The Ministry of Foreign Affairs said last Friday that Cho would visit Russia for his first talks with Morgulov since he took office in May, and a ministry official confirmed his departure for Moscow as planned.

Cho planned to assess situations on the Korean Peninsula during the dialogue and discuss how to deal with the DPRK's nuclear program down the road, the ministry said.

The visit came after Cho held talks with his US and Japanese counterparts Glyn Davies and Shinsuke Sugiyama in June in Washington, and separately met with his Chinese counterpart Wu Dawei in Beijing in the same week.

The disarmament negotiations, which involve the two Koreas, China, the United States, Japan and Russia, were last held in December 2008.

The DPRK walked out of the aid-for-denuclearization talks in April 2009 in protest against fresh UN sanctions, but it recently expressed its wish to return to the negotiating table.

Kim Kye-gwan, DPRK's top negotiator to the long-stalled talks, visited China and Russia earlier this year to draw their supports for the multilateral dialogue.

Recent satellite images indicated that Pyongyang has doubled its nuclear facility. The Washington-based Institute for Science and International Security (ISIS) said on Aug. 7 that the roof size of the building in Yongbyon, which houses centrifuges for uranium enrichment, has doubled since March based on an analysis of satellite photos.

The DPRK said in March that it would restart operations at the Yongbyon nuclear complex by refurbishing and re-operating the five- megawatt graphite moderated reactor that had been mothballed and disabled since October 2007 under an agreement reached at the six- way talks.