By Jon Swaine, New York
A damning report on Ban Ki-Moon has suggested he is overly secretive, tries to censor criticism and allows backroom deals to dictate who gets some top UN jobs, days after he was granted a second term.
The UN Secretary-General is accused of presiding over an "opaque" system, in which senior officials are hired after vacancies are not properly advertised and applicants' backgrounds are not always checked.
Mr Ban, who was eased into a second term earlier this month with no opposition, has not increased transparency in hiring practices, a report by the Joint Inspection Unit (JIU) found.
When confronted with its findings, his office attempted to make changes that "simply eviscerate the entire report" and demanded that their comments on it be kept secret, it said.
The JIU, a team of up to 11 inspectors elected by the UN general assembly, examines various aspects of the UN with the aim of "enhancing the efficiency" of its international operations.
It was asked almost two years ago to investigate the "effectiveness, coherence, timeliness and transparency" of hiring in the UN Secretariat, the executive body headed by Mr Ban.
It looked at the appointment of 150 top-ranking officials, such as Under Secretaries General and Assistant Secretaries General. The jobs are eagerly sought by member states despite being supposedly neutral roles.
It found that, to some member states, the Secretariat's hiring practice "is seen as opaque, raising many questions as to how the process actually works".
While they acknowledge Mr Ban's considerable power in making appointments, concerns were raised about the behind-the-scenes selection process and the fact that "not all vacancies are announced or known to all member states".
"Discretionary authority does not mean that the Secretary-General has carte blanche to avoid the process that he has established," the report said.
"Discretionary authority should not be used as an excuse to avoid transparency".
Mr Ban denies giving out favours but concedes there are "political realities that he must reflect in the organisation", which the JIU described as "tantamount to reserving jobs for member states".
Hillel Neuer, executive director of UN Watch, said: "The growing culture of transparency and freedom of information has not reached the UN. Getting information from it is often like pulling teeth".
Farhan Haq, Mr Ban's spokesman, said secrecy was sometimes necessary to protect candidates' privacy.
"There are a number of useful things in the report that we are studying," said Mr Haq. "We believe the process can be improved".