Nuclear negotiators for Japan and South Korea have reiterated that a dialogue between the two Koreas is a precondition for returning to six-party talks on North Korea's nuclear disarmament.

South Korea's chief nuclear envoy Wi Sung-lac and his Japanese counterpart Shinsuke Sugiyama reaffirmed their positions during a meeting Monday in the South Korean capital Seoul.

The last round of international aid-for-disarmament talks on ending North Korea's nuclear arms programs was held in 2008 in Beijing. Since then, the relations between the two Koreas have worsened. But this year North Korea, supported by China, expressed a desire to return to the aid-for-disarmament talks.

Other parties in the talks, including the United States and Russia, have agreed that the two Koreas should first mend ties.

Sugiyama arrived in Seoul Sunday for a two-day visit ahead of the annual forum of ASEAN states, taking place this week in Indonesia. Japan and South Korea have yet to iron out a recent diplomatic spat over a disputed chain of islets in the Sea of Japan.

Japan's foreign ministry last week ordered a one-month boycott of Korean Air to protest a June 16 demonstration flight by the South Korean airline that passed over the Dokdo islands, which are claimed by both countries.

South Korean officials called the action unacceptable and demanded that Japan immediately withdraw the ban.

The islands, with only a handful of permanent inhabitants, are effectively administered by South Korea, which reclaimed them after emerging from Japanese colonial rule in 1945.

South Korea's Yonhap news agency says that Seoul's foreign ministry issued a statement on Sugiyama's visit without mentioning Dokdo. The report also says Japan showed no signs of reversing the ban, which took effect Monday.