United Nations: The 192-nation UN General Assembly has voted unanimously to elect Ban Ki-moon for a second five-year term as the global body's Secretary-General.

The Assembly unanimously backed the former 67-year-old South Korean foreign minister by acclamation on Tuesday. Ban's second term will commence from January 1, 2012.

With no contenders to throw a challenge for the post, the Assembly approved the new term by consensus. Ban declared his candidacy two weeks ago and had the formal backing by the Security Council on Friday. All regional groups at the UN also endorsed him.

Ban has termed his re-election as a "very great honour beyond expression."

The UN chief's first term has been a mixed bag of experinces.

Ban has faced criticism for not adequately addressing human rights violations in countries like Sri Lanka and China, but has been seen as championing the cause of climate change, women's rights and more recently speaking out against the crackdown on protesters in the Middle East and North Africa.

His role in backing decisive action by the Security Council in Libya and Ivory Coast has also gone down well with the international community.

Ban's re-election was welcomed by US envoy to the UN, Susan Rice. "No one understands the burden of this role, better than he and my government is grateful that he was willing to continue to take them on," she said.

"Secretary-General Ban is a leader who listens to the voices of the voiceless," she said.

Among other agendas, the UN chief will oversee 'Rio+20' next year, which is being dubbed as the most important environmental summit in recent times.