UNITED NATIONS - Ban Ki-moon formally asked the UN Security Council to support his candidacy for a second five-year term as UN secretary-general, according to a letter obtained by Reuters on Monday."As I approach the end of my term of office as the Secretary-General of the United Nations, I am humbly submitting my name for the consideration of the members of the Security Council for a second term," said Ban's letter to Gabon's UN Ambassador Nelson Messone, this month's president of the council.