SEOUL, South Korea — South Korea's foreign minister called North Korea's uranium enrichment program "worrisome" and pressed the communist nation to take real steps toward nuclear disarmament.

Last month, North Korea told the UN Security Council that it was in the final stages of enriching uranium, a process that would give the regime a second way to make atomic bombs in addition to its plutonium-based program.

The claim has raised concerns that the North may add uranium-based weapons to enlarge its stockpile of nuclear bombs made from plutonium. Analysts said at the time that the announcement was aimed at getting the U.S. to accept its demand for direct talks.

On Monday, South Korean Foreign Minister Yu Myung-hwan said the North's new nuclear program is "very worrisome" and said he believes the issue could be separately discussed at the United Nations. He did not elaborate.

North Korea has been reaching out to Seoul and Washington in recent months after months of raising tensions over its nuclear and missile programs, though it conducted short-range missile tests and warned of a naval clash with the South last week.

North Korea's top nuclear negotiator, Kim Kye Gwan, expressed his hopes for "successful talks" with the U.S. and "good future relations" with the United Nations in an interview aired on Monday night.

"I just wish Americans well and everything goes well in the United States," Kim told Fox News Channel's On the Record with Greta Van Susteren. "And I want peace in the United States, so we are committing our own efforts for the good results and good future relations with the United Nations and for successful talks with the United States," he said without elaborating.

Kim made the comments to the Fox News reporter who traveled to Pyongyang last week with the Rev. Franklin Graham, son of American evangelist Billy Graham. The younger Graham, who heads relief agency Samaritan's Purse, was in North Korea to oversee the delivery of $190,000 in equipment and supplies for a new dental school there.

The South Korean foreign minister, however, was skeptical about North Korea's conciliatory gestures.

"There are no real grounds as yet to determine what this softening stance means and if that indicates a fundamental change in its position in the nuclear issue," Yu told a Seoul forum.

Yu said North Korea must first take "substantial" disarmament measures and promptly return to stalled six-party disarmament talks involving the two Koreas, the U.S., China, Russia and Japan.

North Korea has offered to resume key joint projects with South Korea and has proposed direct talks with the U.S., but neither initiative has yet been accepted. Washington and Seoul have also shown no signs of easing pressure on North Korea to disarm through the U.N. sanctions.

Pyongyang's main Rodong Sinmun newspaper urged the South on Monday to end its "confrontation" with the North.

A senior North Korean nuclear negotiator, Ri Gun, was granted a rare visa to visit the United States to attend a private security forum this month, where officials from members of the six-party talks can discuss regional security issues with academics and non-governmental organizations.

State Department spokesman Ian Kelly told reporters Monday that American officials would also attend the Northeast Asia Cooperative Dialogue at the University of California, but there were no bilateral talks with North Korea scheduled to date. Kelly said Ri also plans to attend a New York seminar during his U.S. trip.

A U.S. official said last week that Ri would likely discuss nuclear matters with a senior U.S. diplomat while he was in the United States. The U.S. official spoke on condition of anonymity to discuss sensitive diplomatic contact.