A high-level diplomatic source in Washington close to U.S.-North Korea ties says the North has invited U.S. special envoy on North Korea Stephen Bosworth to the communist state.

The source said it believes Pyongyang extended the invite earlier this month around the time of former U.S. President Bill Clinton's visit to the North to secure the release of two detained U.S. journalists. The source said that both Bosworth and U.S. chief delegate to the six-way talks Sung Kim were invited to come to North Korea some time in September.

If Bosworth accepts the invitation, it will be the first official meeting between North Korea and the U.S. under the Barack Obama administration.

However, the U.S. State Department made it clear in a Monday briefing that Washington is willing to talk with Pyongyang bilaterally, but only in the six-party multilateral context.

Apart from the possible North Korea trip, Bosworth will again visit South Korea, Japan and China this month or early next month to discuss the North Korean nuclear issue.