WASHINGTON, Oct. 25 (Yonhap) -- After two days of high-level talks in Geneva, North Korea and the United States said Tuesday that there was some progress but no concrete deal.

The North's chief delegate said the meetings produced "big progress," but U.S. officials chose more diplomatic and careful wording.

"While there's been some narrowing of differences, we haven't had any breakthroughs here and significant issues do remain...

There is quite a bit of work still to do," State Department spokeswoman Victoria Nuland said at a press briefing.

She did not specify what the outstanding issues are.

She suggested that the U.S. is open to further talks with the North.

"No onward meeting has been set, although we haven't closed the door on it, either," she said. "I think we need some digestion time."

Nuland said the U.S. and North Korean delegates had Korean food for lunch together, indicating a rare amicable mood.

In Geneva, the outgoing U.S. envoy on Pyongyang described the discussions with the North as "positive and generally constructive."

"There's a long history to this relationship and we have many differences, not all of which can be overcome quickly," Stephen Bosworth told reporters. "I am confident that with continued effort on both sides, we can reach a reasonable basis of departure for formal negotiations for a return to the six-party process."

Bosworth was referring to the six-way talks on ending Pyongyang's nuclear weapons drive. The talks, also joined by South Korea, China, Russia and Japan, have been stalled for the past two years, a period marked by provocations by the North and a sudden return to peace overtures.

Bosworth said the two sides will keep in touch through the so-called New York channel -- the North's mission to the United Nations.

North Korean Vice Foreign Minster Kim Kye-gwan, however, struck a more positive tone.

"There was a set of big progress," he said, adding the two sides agreed to meet again for discussions on remaining issues.

"We focused on discussing trust-building measures to improve North Korea-U.S. relations as agreed in the first round of talks (in New York in July)," Kim said.

In the New York session, the U.S. reportedly demanded Pyongyang take initial steps to prove its seriousness about denuclearization, including a halt to its uranium enrichment program, a return of international inspectors to its main nuclear facilities, a moratorium on nuclear and long-range missile tests, and improved ties with the South.

U.S. officials said they used the Geneva talks to touch on "all issues" such as a possible food aid for the North, reunions for separated families and other humanitarian issues.

The State Department spokeswoman reiterated that Washington does not link food aid with the political landscape.

"We haven't made any decisions on food aid. We didn't make any decisions in this context," Nuland said, facing a barrage of questions on the matter.

Western reporters claim that Washington is using a double standard by easing restrictions on assistance to Somalia and other nations in the Horn of Africa.

Nuland stressed the importance of making sure food, if provided, will go to ordinary people in need in North Korea, not the ruling elite.

On the timing of Bosworth's departure as envoy on Pyongyang, the spokeswoman said he will quit as soon as he comes back to the U.S. and completes a debriefing on the Geneva talks.

Glyn Davies, ambassador to the International Atomic Energy Agency, took part in the talks in his capacity as the next special representative for North Korea policy.

Meanwhile, South Korean government officials reacted cautiously to the reported outcome of the talks.

"It is premature to assess (that)," a Seoul official said. "We will review the direction of follow-up dialogue after being debriefed by the U.S."