Updated

North Korea must show it is serious about abandoning its atomic weapons programs before long-stalled disarmament negotiations can resume, South Korea's lead negotiator said Monday.

The comments by Wi Sung-lac came as North Korea's foreign ministry reiterated its call for the aid-for-disarmament talks to start soon and without preconditions.

The diplomatic maneuvering by the rival Koreas follows recent discussions between North Korean officials and their counterparts in Seoul and Washington that have led to hope that negotiations to end North Korea's nuclear aspirations could begin again.

Trying to settle the North's push to expand its arsenal of nuclear weapons has become especially urgent after bloodshed over the past year saw the two Koreas threatening war. In the 2 1/2-year break since the last round of disarmament talks, alarm has risen over two deadly attacks on South Korea that Seoul blamed on Pyongyang and a continued advancement in North Korea's nuclear work.

Wi, speaking with foreign reporters in Seoul, indicated that despite recent cordial talks between him and his North Korean counterpart, there's still a long way to go before negotiators from the six nations involved in the formal nuclear talks can sit down again. Asked if the talks might resume this fall, he said such a timetable was "too aggressive, too ambitious."

Wi wouldn't discuss specifically what nuclear measures North Korea must take, but said "concrete action" by Pyongyang must precede a return to nuclear negotiations.

Wi said recent talks with North Korea are a positive sign. But his comments suggest that it is not clear whether North Korea is willing to give negotiators what they've wanted since the talks began in 2003: Real evidence that Pyongyang will walk away from its nuclear programs in exchange for aid and better ties with the United States and the North's neighbors.

North Korea said Monday it is prepared to carry out a past agreement to dismantle its nuclear program in exchange for aid, and called for a quick resumption of talks without preconditions. Although it is the first official word from Pyongyang since a senior North Korean diplomat visited New York last week for rare talks with U.S. counterparts, the comments repeat a long-standing North Korean call for new disarmament negotiations.

North Korea is pushing for nuclear talks ahead of celebrations next year to mark the centennial of the birth of late President Kim Il Sung, who founded the country and is the father of current leader Kim Jong Il. Pyongyang is seen as wanting a diplomatic breakthrough with the United States, its wartime adversary, as well as a peace treaty to formally end the Korean War. The country has also faced a dramatic drop in outside aid and exports due to sanctions.

After last week's talks in New York, the United States said it would consult with South Korea and other countries involved in six-nation talks. Washington characterized the meetings as exploratory, and officials from both countries described them as "constructive and businesslike."

Pyongyang pulled out of the disarmament talks in April 2009 after being condemned for launching a long-range rocket considered a violation of a ban on nuclear and missile-related activity.

The Korean peninsula remains in a technical state of war because the three-year Korean War ended in a truce, not a peace treaty, in 1953.

Tensions have been high since conservative South Korean President Lee Myung-bak took office in 2008 seeking to link aid to nuclear disarmament.

The animosity reached a peak after the North bombarded a front-line South Korean island with artillery in November, killing four people. The South also holds the North responsible for the deaths of 46 sailors on a warship that sank in March 2010, but North Korea denies the allegations.