Ban Ki-moon was re-elected as secretary general through applause without a vote [EPA]

The 192-nation U.N. General Assembly on Tuesday unanimously approved a second five-year term for Secretary-General Ban Ki-moon beginning Jan. 1, 2012.

The former South Korean foreign minister, who took over from his predecessor Kofi Annan in January 2007, was re-elected to the world body's top job through applause without a vote.

Today’s decision follows a recommendation last week by members of the Security Council that Mr. Ban – the eighth person to serve as UN chief – be re-appointed. He has been in office since January 2007.

Ban declared his candidacy two weeks ago and was given the UN Security Council's formal backing on Friday.

Joseph Deiss, president of the General Assembly, praised Ban for "his remarkable leadership" and for having "strengthened the role and visibility of the UN".

"In a complex, difficult international environment, you have strengthened the role and the visibility of the United Nations by adopting reform measures; launching exciting, innovative initiatives; and calling faithfully and constantly for respect for human rights, the rule of law and the other values rooted in our Charter,” Deiss told the assembly.

Ban has said climate change - a topic the United Nations struggled with during his first five years - is his top challenge. He has called the battle against global warming "the most important priority" for mankind.

The UN chief has also vowed to keep speaking up for the protesters taking on long-ruling leaders in the Arab world.

Ban, 67, has been outspoken in faulting the leaders of Arab countries facing pro-democracy protests, but has at the same time garnered criticism from some human rights groups.