Top U.S. nuclear negotiator Christopher Hill will reportedly visit North Korea to discuss that country's reporting of its nuclear programs.

A diplomatic source in Seoul says the U.S. envoy will come to South Korea around this weekend. His trip to Seoul will come either right before or after a visit to Pyongyang.

The source said that before Hill visits the North, State Department Korean affairs expert Sung Kim will likely go first for preliminary talks.

North Korea is known to have conveyed its commitment to reporting all nuclear programs though the process hasn't yet begun. A key concern is whether that declaration will include the North's suspected uranium program.

The source also said the six-way chief delegates' meeting slated to begin December sixth may be delayed.