UNITED NATIONS — South Korea's Ban Ki-moon was sworn in Thursday as the eighth secretary-general of the United Nations, promising to make his top priority the restoration of trust in the world body that has been tarnished by corruption scandals.

Ban, 62, will take the reins of the United Nations on Jan. 1 when Kofi Annan steps down after 10 years at the helm. He will be the first Asian to lead the organization in 35 years

Ban will oversee an organization with some 92,000 peacekeepers around the world and a $5 billion annual budget. Its reputation has been battered by scandals in the oil-for-food program in Iraq and in peacekeeping procurement, and its outdated practices need reform to meet the challenges of the 21st century.

General Assembly President Sheikha Haya Rashed Al Khalifa administered the oath of office to the career diplomat who served as South Korea's foreign minister. Ban swore to conduct himself solely in the interests of the United Nations and to refuse to accept instructions from any government or other authority.

In a brief address, Ban told delegates from the 192 U.N. member states that he was "deeply mindful" of key words in the oath — "loyalty, discretion and conscience" — which he said "will be my watchwords as I carry out my duties as secretary-general."

He pledged "to set the highest ethical standard" and "work to enhance morale, professionalism and accountability among staff members, which in turn will help us serve member states better, and restore trust in the organization."

"The good name of the United Nations is one of its most valuable assets — but also one of its most vulnerable," Ban said.