"The report is critical of me personally, and I accept its criticism," he told the Security Council on Wednesday after receiving the latest report by a panel led by former US Federal Reserve Board chairman Paul Volcker.
"As chief administrative officer, I have to take responsibility for the failings revealed," Annan said. Earlier, Volcker told the council that responsibility for the scandal "must be broadly shared."
"The responsibility for the failures must be broadly shared, starting, we believe, with member states and the Security Council itself," he said.
The UN chief also conceded that he was "not diligent or effective enough" in pursuing an investigation after he learned the Swiss company Cotecna that employed his son Kojo had won a large contract under the oil-for-food program.
"I deeply regret that," he said.
"The evidence of actual corruption among a small number of UN staff is also profoundly disappointing for all of us who work in the organization," Annan said, conceding that the management of the program was marked "by weak administrative practices and inadequate control and auditing".
"The inquiry's findings underscore the vital importance of proposed management reforms, many of which are at this very moment being negotiated among member states in the General Assembly," he added.
In a preview of its report released on Tuesday, the Volcker panel said its investigation had revealed "serious instances of illicit, unethical and corrupt behavior within the United Nations" that had been allowed to flourish because of poor administration.
While noting that the UN Charter designates the secretary general as chief administrative officer, it argued that the post had evolved into one where the primary role was that of the UN's top diplomat.
"In these turbulent times, those responsibilities tend to be all-consuming. The record amply reflects consequent administrative failings," the panel said, citing "a grievous absence of effective auditing and management controls".
The oil-for-food program - which ran from 1996 to 2003, when US-led forces invaded Iraq to oust President Saddam Hussein - allowed Baghdad to sell oil to raise money for humanitarian goods the country lacked due to sanctions.
Volcker's report said those managing the program - both UN member states and the world body's staff - failed the ideals of the United Nations, ignoring clear evidence of corruption and waste that flourished after the UN was created in 1996.
"The inescapable conclusion from the committee's work is that the United Nations organization needs thorough reform - and it needs it urgently," the report said.
The report's conclusions and its strong urging for change come a week before world leaders gather for a summit in New York to consider a host of Annan's own reform initiatives.
Many of his proposals have stalled - including ones similar to the committee's - because of deep divisions among member states. The United States and other supporters of UN reform hope the report will provide much-needed impetus.
Annan accepted the criticism in a briefing to the council.
"The findings in today's report must be deeply embarrassing to us all," Annan said. "The Inquiry Committee has ripped away the curtain, and shone a harsh light into the most unsightly corners of the organization. None of us - member states, Secretariat, agencies, funds and programs - can be proud of what it has found."
Despite the criticism of him and his deputy, Annan told reporters afterward: "I don't anticipate anyone to resign. We are carrying on with our work."
The report is not shy about assigning blame. It says that France and Britain were cooperative.
Russia and China, on the other hand, refused requests for information or access to state-owned companies implicated in the investigation. While some branches of the US government were helpful, notably the US mission to the UN and the
State Department, others were not.
It also described a plot in which the Iraqi government, which wanted UN sanctions lifted, tried to influence Annan's predecessor, Boutros Boutros-Ghali, and later Annan's coordinator for UN reform, Canadian businessman Maurice Strong.
Baghdad paid millions of dollars to South Korean businessman Tongsun Park and Iraqi-born American businessman Samir Vincent, with the apparent expectation that they would pass money to Boutros-Ghali and Strong. Vincent has pleaded guilty to skimming money from the program.
But the report found no evidence that Boutros-Ghali ever took money from Iraq or that Strong was involved in oil-for-food or did anything at their request.
The committee criticised Boutros-Ghali for allowing the oil-for-food programme to be established in a way that enabled Saddam to exploit it.