The secretary-general had decided not to take action last summer after a U.N. investigation. He says he had received legal advice that the accusations could not be proven. Mister Annan now says the continuing dispute had "made the high commissioner's position impossible." But he says his acceptance of the resignation does not mean that Mister Lubbers is guilty.
Mister Lubbers completed more than four years of a five-year term as head of the refugee agency.
Mister Annan recently appointed Mark Malloch Brown as his top aide. Mister Malloch Brown headed the U.N. Development Program. The new chief of staff is seen as more aggressive than Mister Annan. U.N. diplomats told The Associated Press that he was the one who first informed Ruud Lubbers that Mister Annan wanted him to leave.
The United Nations has struggled recently to improve its public image. The U.N. has been criticized for failing to supervise the oil-for-food program in Iraq. And U.N. peacekeepers have been accused of sex crimes against Congolese women and children.
Last week, writing in the Wall Street Journal, the secretary-general argued that the U.N. remains important to humanity. He offered examples of efforts to help people around the world. One was the U.N. reaction to the tragedy from the tsunami waves in the Indian Ocean in December.
World leaders are to consider reforms for the United Nations when they meet in New York in September. Mister Annan says he will have proposals for, in his words, "making the U.N. work better, and the world fairer and safer."
This VOA Special English Development Report was written by Jill Moss. I'm Gwen Outen.