The United States and North Korea remain far apart after exploratory talks on Pyongyang's nuclear disarmament but both sides are trying to narrow the gap, the United Nations chief was quoted as saying.

North Korea's first vice foreign minister Kim Kye-Gwan held talks in New York with US officials last Thursday and Friday as part of diplomatic efforts to restart long-stalled six-nation nuclear negotiations.

"There is still a considerable distance between the two sides and it can't be concealed," UN secretary-general Ban Ki-moon was quoted as saying by South Korea's Yonhap news agency.

"But there will be efforts to narrow the gap," he told South Korean correspondents in New York on Tuesday, citing information from working-level channels. "It is inspiring that both the US and North Korea said so."

The talks, the first high-level US-North Korean contact since December 2009, followed a rare meeting last month between the South and North Korean nuclear negotiators in Bali.

"What is important is that there was contact (with North Korea). I think it is going in the right direction," Ban told correspondents ahead of his trip to South Korea next week.

The two rounds of talks will "make positive contributions to continuing to develop dialogue, easing tensions on the Korean peninsula and building up trust among concerned parties in the six-way talks," the former South Korean foreign minister said.

The North's Kim said separately he was satisfied with last week's meeting.

"I am satisfied with talks this time... (and) will continue the dialogues down the road," Yonhap quoted him as saying in New York before leaving for Beijing en route to Pyongyang.

Kim called for "more bilateral talks" before resuming the six-party forum which has been stalled since December 2008, Yonhap said.

The North's foreign ministry said Monday it wants a quick resumption of the full six-party talks, which group the two Koreas, the United States, China, Russia and Japan.

It termed the New York talks "sincere and constructive" and said the two sides had agreed to hold further dialogue.

Kim reiterated the North's claim that its uranium enrichment programme disclosed last November is a peaceful energy project, Yonhap said.

Experts say it could easily be reconfigured to produce weapons-grade uranium to augment the country's plutonium stockpile.