UN Secretary General Ban Ki-moon said Friday he was encouraged by "positive discussions" in Berlin on North Korea's nuclear programmes and urged the resumption of six-party talks, DPA reported. The UN did not elaborate on the discussions. In Seoul, US chief negotiator Christopher Hill on Friday denied a North Korean report that US and North Korean negotiators had reached an agreement following three days of face-to-face talks in Berlin this week. North Korea's official Korean Central News Agency (KCNA) Friday quoted a spokesman saying North Korea had reached a "certain agreement" with the United States. A spokesman at UN headquarters in New York said Ban "welcomes reports of active preparations for the next round of the six-party talks on denuclearization of the Korean peninsula. He was encouraged in particular by the recent positive discussions in Berlin between the Democratic People's Republic of Korea and United States negotiators." The six-party talks, among the US, Russia, China, Japan and the two Koreas, are slated to resume sometime in February.