UNITED NATIONS – The dispute between representatives of the United Nations staff council and the organization’s top internal investigator is widening, as the investigator fired the latest salvo in a published interview, saying that the staff council’s allegations against him are “wild” and “made to agitate.”

The attack on the council, the union representing Turtle Bay staff members, might become an issue in a crucial meeting tomorrow. Council representatives are scheduled to meet with besieged Secretary-General Annan to clear the air between staffers and management, at a time that outside attacks on Mr. Annan are gaining momentum.

Singaporean national Dileep Nair, who heads the U.N. in-house investigative arm, known as the Office of Internal Oversight Services, told an online publication that contrary to claims by U.N. officials about a fresh probe into allegations against him, he had been promised by Mr. Annan’s chief of staff, Iqbal Riza, that there will be no new investigation.

“I have been reassured by the chef de Cabinet that there will not be any reopening of the inquiry,” Mr. Nair was quoted as saying by Tor Ching Li of the Singapore-basedToday.com, confirming suspicions that no new probe would be carried out.

His assertion seemed to contradict a promise made to representatives of the staff council at a meeting last week with the undersecretary general for management, Catherine Bertini, who according to sources on both sides promised that she would investigate any further allegations the council raises.

The meeting last week came in the wake of Mr. Nair’s recent exoneration six months after the council originally called for an investigation. Ms. Bertini said she found no wrongdoing by Mr. Nair, but council members scoffed at her investigation, calling it a “whitewash.”

Ms. Bertini, according to a U.N. source, looked into several allegations that appeared in a staff resolution claiming that Mr. Nair had strayed from U.N. practices in hiring decisions, favoring his allies and overlooking others. That probe was described by spokesman Fred Eckhard as “thorough.” It found that “everything was done by the book,” he told The New York Sun.

Allegations that two women exchanged sexual favors with Mr. Nair for promotion were also checked. Ms. Bertini found those allegations “not credible enough,” according to a U.N source who added that for such an investigation to go any further, the organization would have to hire an outside investigator, since Mr. Nair, the accused in this case, is the resident in-house investigator.

The staff council is preparing a list of questions that are still unanswered, one official who is familiar with the union negotiators’ stance told the Sun. Officials on Mr. Annan’s side say that the ball is now in the union’s court to produce what Mr. Eckhard described as “fresh information,” so Ms. Bertini could take a “fresh look” into it.