EVEN before he takes up his post as the new United Nations Secretary-General, Ban Ki Moon, the man certain to become the world’s top diplomat found himself embroiled yesterday in his first major international crisis.

The South Korean Foreign Minister, who will be confirmed in his new job on Monday by the UN Security Council, said that his priority would be to engage the regime of Kim Jong Il, which has threatened to detonate an underground nuclear device, possibly this weekend.

Dealing with the crisis in North Asia is typical of the work that Mr Ban can expect from January when he moves into the office occupied by Kofi Annan, who once memorably described his post as “the world’s most impossible job”.

While the UN Charter neatly sums up the duties of the Secretary-General as the “chief administrative officer”, it does not do justice to the complexity of the work. The Secretary-General has a three-layered role that some have likened to a secular Pope and others have compared to running a dysfunctional multinational corporation.

The UN leader runs a staff of nearly 17,000 employees and oversees a multi-billion dollar budget. He must also lead campaigns against poverty, Aids and other global calamities.

He has to be a consummate diplomat, to juggle the demands of the world’s great powers, as well as represent the smallest and poorest of the 191 member states.

Finally, he is the fireman sent out to put out the flames in North Korea, the Middle East and other world hotspots.

In Seoul, Mr Ban is best known for his bureaucratic skills, which have earned him the nickname “Ban Chusa”, or administrator in Korean.

Journalists at the Foreign Ministry have a less flattering name for Mr Ban, who is called the “slippery eel” for his ability to slither out of difficult questions.

The most damning criticism of the 62-year-old is his lack of charisma. He is colourless to the point of invisibility and even veteran Asian experts admit that they had not heard of him until his name was put forward to run the UN.

“He is competent, clean and careful, and these are all qualities you want as a Secretary-General, but he has not done anything to distinguish himself either as foreign minister or before,” said Peter Beck, the head of the International Crisis Group’s Seoul office. “He has no tangible achievements under his belt.”

Mr Ban, a diplomat of 35 years standing who is married with one son and two daughters, defended himself this week. “I may look soft from the outside but I have inner strength when it is really necessary. I have always been very decisive,” he said earlier this week. “In Asian countries, humility is regarded as a virtue. Soft-speaking should in no way be regarded as a lack of leadership or commitment.”

Mr Ban can claim credit for running one of the slickest campaigns to win backing for the Secretary-General’s post.

He secured support from America and China, and with the full and generous backing of his government eclipsed the other six candidates, who have now all dropped out.

Some UN observers believe that an uncharismatic, weak Secretary-General can be very effective because he is less likely to challenge powerful players at the UN, particularly the permanent members of the Security Council.

Mr Ban, it is predicted, will last longer if he is more “secretary” than “general”.

Certainly, Mr Ban is not short of ambition. At the age of 18 he won an English speech-writing competition and was invited to the White House to meet President John F. Kennedy. It was there that he decided to become a diplomat. Half a century later he is about to reach the pinnacle of his profession.

THE UNITED NATIONS IN NUMBERS

The budget for 2006-07 is $3.7 billion (£2.1bn)

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