Defense Secretary Leon Panetta expressed scepticism Thursday about the outcome of US talks with North Korea, days after a second round of discussions was held in Geneva.

"The word scepticism would be in order at this time as to what may or may not happen in those discussions," he told reporters during a visit to South Korea.

The talks Monday and Tuesday, following up a meeting in New York in July, were intended to pave the way for the resumption of six-nation negotiations on the North's nuclear disarmament.

Panetta said there were indications some progress was made but no agreement was reached and it was unclear where the talks were headed.

US Assistant Secretary of State Kurt Campbell said earlier Thursday the Geneva discussions made some progress but no breakthrough.

"There is a substantial amount of work that needs to be done. No decisions have been taken about next steps," Campbell told journalists during a stopover in Seoul.

"We clearly stated our position on pre-steps," he said, without elaborating.

The North formally quit the six-party nuclear talks in April 2009, a month before staging its second atomic weapons test.

It has since repeatedly said it wants to come back without preconditions to the negotiations, which group the two Koreas, the US, China, Russia and Japan.

Washington and its allies say Pyongyang must first take steps to show its sincerity, such as shutting down a uranium enrichment plant that could be converted to make nuclear weapons.

North Korea said Thursday the Geneva talks made progress and the two sides would hold further meetings.

"Both sides decided to further... contacts and talks to discuss and solve the pending issues in the light of building confidence," a foreign ministry spokesman told Pyongyang's official news agency.

However, the spokesman reiterated that the full six-nation nuclear negotiations should restart without any preconditions.