South Korea's top nuclear envoy left for Japan Tuesday to discuss ways to revive six-party talks on North Korea's nuclear disarmament, after Pyongyang announced it would shun dialogue with Seoul.

South Korea and several other parties to the talks -- which group the two Koreas, the United States, China, Russia and Japan -- want a three-step approach to restart the dialogue after more than two years.

This envisions inter-Korean talks, followed by talks between Washington and Pyongyang and the resumption of the full negotiations which the North quit in April 2009, a month before its second atomic weapons test.

Last month, however, Pyongyang announced it would no longer deal with Seoul's conservative government following months of high tensions.

"Since North Korea recently announced it will no longer engage with the South, there's a need to prop up the approach that starts with inter-Korean dialogue," Seoul's envoy Wi Sung-Lac was quoted as saying by Yonhap news agency.

"With regard to ways to resume the six-party talks, it's important to strengthen cooperation between South Korea, Japan and the United States. Japan is an important partner that has agreed with our approach from the start."

Wi will meet Shinsuke Sugiyama, his Japanese counterpart, during a two-day visit.

Last week he visited China, the North's sole major ally, for talks with his counterpart there, Wu Dawei.

He also held talks with US Assistant Secretary of State Kurt Campbell and Russia's deputy nuclear envoy, Grigory Logvinov, in Seoul last Friday.

Efforts to restart the forum have been hamstrung by tension on the Korean peninsula since two deadly border incidents last year which the South blames on the North.

Pyongyang also fuelled regional security fears last November by disclosing a uranium enrichment plant, which could give it a second way to make atomic bombs.

It further chilled the mood for inter-Korean dialogue with its vow to halt dealings with Seoul, and its disclosure of a secret meeting between the two sides.

earlier related report
N. Korea leases port pier to Switzerland: report
Seoul (AFP) June 14, 2011 - North Korea has leased a pier at a northeastern free trade zone to Switzerland as part of attempts to attract badly needed foreign investment, a report said Tuesday.

South Korea's Yonhap news agency said Pyongyang had forged the deal to lease one of the piers at Rajin port, in its Rason special economic zone bordering China and Russia.

It gave no details of the reported Swiss deal but said Pyongyang last year leased two other piers at the port on the Sea of Japan (East Sea), one to China for 10 years and another to Russia for 50 years.

A group of Swiss foreign ministry officials led by Beat Nobs, deputy secretary of state, arrived in Pyongyang on Monday, the North's state media said.

The Swiss embassy in Seoul could not immediately confirm the report.

Yonhap's source said some European companies also plan to invest in Rason, formerly known as Rajin-Sonbong.

The impoverished communist state is striving to revitalise its economy through foreign investment in Rason, which was declared a special economic zone in 1991 but failed to flourish.

In January this year a South Korean newspaper reported that China plans to invest about $2 billion to build up Rason as a regional export base. The port would give China's northeastern provinces direct access to the Sea of Japan.

China, Pyongyang's sole major ally and biggest trade partner, is actively exploring investment opportunities in North Korea as South Korea's economic influence dwindles amid political tensions.