South Korea's top nuclear envoy will visit China this week to discuss ways to resume long-stalled nuclear disarmament talks on North Korea, Seoul's foreign ministry said Tuesday.

Lim Sung-Nam, Seoul's envoy for the six-nation denuclearisation forum, will meet with his Chinese counterpart Wu Dawei and other Beijing officials on a two-day trip beginning Wednesday.

Lim "will exchange opinions on the latest situation on the North and its nuclear issues", ministry spokesman Cho Tai-Young said.

The six-party nuclear disarmament forum is chaired by China and comprises the two Koreas, Japan, the United States and Russia.

The full forum last met in December 2008. In April 2009, North Korea announced it would take no further part and, a month later, conducted its second nuclear test.

Pyongyang also disclosed in November 2010 an apparently operational uranium enrichment plant -- a second potential way of building a nuclear bomb on top of its plutonium stockpile.

The UN atomic agency IAEA last week called the North's nuclear programme a "serious concern", pointing to significant progress in recent months in building a new light-water reactor.

The North says the reactor is necessary to meet its energy needs.