A senior UN official left Pyongyang on Saturday after four days of talks with the North Korean Foreign Ministry.
"I have to brief the secretary general first" was all UN Undersecretary General for Political Affairs Jeffrey Feltman said when asked for details of his trip.
Feltman met North Korean Foreign Minister Ri Yong Ho on Thursday and also had two sessions of talks with Vice Foreign Minister Pak Myong Guk.
Feltman, the highest-ranking American in the UN secretariat, is the first person in that post to visit North Korea since February 2010. Though Feltman previously worked for the State Department, he is not representing the US government.
North Korea regularly accuses the UN of bias, criticizing the UN sanctions resolutions that condemn Pyongyang's missile launches and nuclear tests. Pyongyang says those resolutions are illegal, insisting it has the sovereign right to pursue its missile and nuclear programs because of what it sees as a serious threat from the United States.
North Korea has also recently expressed concern about the latest sanctions affecting the ability of UN aid agencies to help the needy in North Korea.
North Korea requested this week's visit, the UN. said.
Six UN agencies, with approximately 50 international staff, are represented in North Korea.