UNITED NATIONS - United Nations Secretary-General Ban Ki-moon Wednesday reacted graciously to last weeks leaked memo from Norways UN Ambassador lambasting his leadership, saying he always welcomes constructive criticism. Ban told an impromptu news briefing that he would go ahead with his upcoming visit to Norway, despite the controversy caused by the memo, which he described as an internal Norwegian document. Ban flies to Austria on Thursday and from there to Norway in an effort to focus worlds attention on consequences of melting North Pole glaciers. The UN is set to hold a summit meeting on Climate Change on September 23. Questioned about the leaked memo, in which Norways Deputy UN Ambassador Mona Juul said the Secretary-General suffered from a lack of charisma, UN chief Ban said it was an internal report for Norway and he had no comments. He said it was the job of UN ambassadors to file their assessments to their respective governments. At the same time, Ban said he welcomed criticism or suggestions - if made in a constructive spirit - as they helped him to improve upon his performance. The Secretary-General said Norways Foreign Minister Jonas Gahr Stoere had called him on Tuesday and assured him of his government full support, pledging to further strengthen the countrys relations with the UN. Norway, he said, was a strong and active supporter of the UN. Soon after the memo appeared in the Aftenposten newspaper last week, the Norwegian foreign minister said it was unfortunate that it had been leaked to the press. I regret that it happened, but let me stress that this is a report to the Norwegian Foreign Ministry, it was not a statement by the Norwegian government, Stoere said. Norwegian Ambassador Juul accused Ban, a former South Korean foreign minister, of weak, ineffective and at times counterproductive leadership. Ban is halfway through a five-term stint as Secretary-General. He took over as UN Secretary-General on January 1, 2007.At the same time, Ban said he welcomed criticism or suggestions - if made in a constructive spirit - as they helped him to improve upon his performance. The Secretary-General said Norways Foreign Minister Jonas Gahr Stoere had called him on Tuesday and assured him of his government full support, pledging to further strengthen the countrys relations with the UN. Norway, he said, was a strong and active supporter of the UN. Soon after the memo appeared in the Aftenposten newspaper last week, the Norwegian Foreign Minister said it was unfortunate that it had been leaked to the Press. I regret that it happened, but let me stress that this is a report to the Norwegian Foreign Ministry, it was not a statement by the Norwegian government, Stoere said. Norwegian Ambassador Juul accused Ban, a former South Korean foreign minister, of weak, ineffective and at times counterproductive leadership. Ban is halfway through a five-term stint as secretary-general. He took over as UN Secretary-General on January 1, 2007.