Former South Korean Ban Ki-moon has asked for the support of UN Security Council for his candidacy for a second five-year term as U.N. secretary-general.

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, Ban said in a letter to Gabon's U.N. Ambassador Nelson Messone.

Ban, whose first term ends on December 31, had already received assurances of support from the United States and other key members of the U.N. Security Council.

In his four-and-a-half years as the U.N. chief, Ban said he had a good understanding with the 15-nation council and found common ground on critical global issues of peace and security -- from Somalia to Sudan, Cote d'Ivoire (Ivory Coast) to Afghanistan, Iraq and the Middle East and far beyond.

Ban said his push to make climate change a top concern for governments around the world was one of his major accomplishments since he took the helm of the world body in January 2007.

The U.N. General Assembly elects U.N. secretaries-general on the recommendation of the Security Council. It is the five permanent veto-wielding council members -- Britain, China, France, Russia and the United States -- that decide who gets the job.

After being decided, the decision is then approved by the full council and the assembly, U.N. diplomats said. They further added that the formal re-election process for Ban should be over by the end of June.