Beijing - China extended congratulations to Ban Ki-moon upon his election to serve a second five-year term as secretary-general of the United Nations, and hoped he would play a bigger role in promoting international cooperation and world peace.

Chinese Foreign Ministry spokesman Hong Lei said: "China will continue to support Ban's work and the work of the United Nations".

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China also recognized Ban for his work during his first term, when he helped to ensure the UN continues to play an important role in international affairs.

Ban, 67, was inaugurated in 2007 and is the first UN chief to hail from an Asian country in the past four decades. On Tuesday, he won unanimous approval for his re-election as head of the 192-member organization. His second term will begin on Jan 1.

Ban has won praise for his work on climate change, UN peacekeeping operations, disarmament, the empowerment of women and other issues.

Li Baodong, the Chinese UN representative, told reporters during an interview this month that Asian countries were very enthusiastic about Ban's candidacy, saying he has demonstrated "strong leadership" and shown he is a "person of action".

Ban, in a speech after he had taken the oath of office on Tuesday, pledged that UN member states will work together to "find unity in action out of the competition of ideas". Quoting the Chinese philosopher Lao-tsu, he said: "The way of heaven is to benefit others and not to injure. The way of the sage is to act but not compete."

Lee Myung-bak, president of the Republic of Korea, congratulated Ban over the phone on Wednesday over his re-election. During the conversation, Lee said he was proud that "people around the world hold high views" of the former ROK foreign minister and that "all citizens of the ROK rejoiced" over Ban's re-election.

Ban's victory also drew attention and discussion from Chinese Internet users.

Waijiao Xiaolingtong, the Foreign Ministry's microblog account at weibo.com, the Chinese version of Twitter, quickly posted the ministry's congratulation message to Ban online on Wednesday morning. Chinese Internet users who commented after the post expressed wishes that Ban will work harder toward ensuring world peace.

At the same time, Chinese netizens raised some concerns. A commenter going by the name Xi You said Ban should be tougher in dealing with the United States and other large powers.

There are three reasons why Ban managed to win a second term, according to Zheng Qirong, vice-president of China Foreign Affairs University and an expert on UN affairs.

"The first is that there is an unwritten rule stipulating that the secretary-general generally will succeed in seeking a second term and Ban did well in his first term," Zheng said. "Second, Ban himself is also an important reason. He is fairly inconspicuous and is on good terms with the member states. And his origin in an Asian country also matters, since the region is now growing very quickly," Zheng told China Daily on Wednesday.

In his speech on Tuesday, Ban emphatically stated that "no challenge is too large". But the future will not be smooth. Among the difficulties Ban will encounter will be the nuclear issues in Iran and the Democratic People's Republic of Korea and terrorism issues. There is also the responsibility of trying to meet the UN's Millennium Development Goals, which call for greatly reducing world poverty by 2015, which will come during Ban's second term, according to Zheng.

"It is definitely not an easy job," Zheng commented.

"But the United Nations as the chief means of resolving international conflicts will not change in the near future."

Yonhap News Agency and Xinhua contributed to this story.