Talks between the United States and North Korea on resuming stalled nuclear negotiations have ended in Geneva, with a U.S. official calling them “positive and constructive.”

That description was given by the U.S. special envoy for North Korea, Stephen Bosworth, who said he is confident the two sides can eventually reach a deal. He said they narrowed some differences during the Geneva meetings, but did not elaborate.

Bosworth said the two delegations will report back to their respective capitals and remain in contact through the North's United Nations' mission in New York.

The six-party talks are aimed at getting North Korea to end its nuclear weapons program in return for diplomatic and economic concessions. These include a provision for electric power from South Korea.

North Korea pulled out of the talks in 2009, and both Washington and Seoul are concerned about recent disclosures that Pyongyang has a sophisticated uranium enrichment program.

The six-party talks include the United States, North and South Korea, Russia, Japan and China.