A government source in Seoul told the agency Vice Foreign Minister Kim Kye-gwan was expected to arrive in New York Thursday on the invitation of think-tank groups, as the United States doesn't formally recognize North Korea.
Kim was Pyongyang's chief nuclear negotiator before he was promoted to his current position.
His trip will reportedly include a meeting with U.S. envoy Stephen Bosworth, sources told Yonhap. That would mean the resumption of talks on the North's nuclear programs after 19 months of stalemate.
Elsewhere, South Korean government sources said evidence had emerged the North had conducted a test of a long-range missile engine weeks before last November's shelling of a disputed island.
The officials said the launch from the Dongchang-ri site in the northwest was apparently done at a time when Pyongyang knew U.S. satellites could observe it, Yonhap said.