The U.N. security chief resigned Tuesday over the Dec. 11 Algiers truck bombings after an expert panel found "gaps and weaknesses" in the U.N.'s overall security operations due to cost-cutting.

The bombings at U.N. offices and another government building killed 17 U.N. staffers and injured 40 others, many seriously.

David Veness, the U.N.'s undersecretary-general for security and safety, voluntarily offered his resignation and "was willing to shoulder full responsibility for any security lapse that may have occurred" in Algiers, Secretary-General Ban Ki-moon said.

"The report recognizes that risk management is not consistently understood or applied," Ban said.

The U.N. chief also highlighted the panel's conclusion there was "ample evidence that several staff members up and down the hierarchy may have failed to respond adequately to the Algiers attack, both before and after the tragedy."

Ban said for the sake of continuity, he would retain Veness for "some time" until a successor is named. Veness has served as the top U.N. security official since January 2005. Before that he was an assistant police commissioner in London.

The bombings added to the U.N.'s increasing worry that its staff and missions are becoming more of a target worldwide.

In claiming responsibility for the attack, Al-Qaida in Islamic North Africa called the U.N. offices "the headquarters of the international infidels' den." The other site targeted that day was Algeria's Constitutional Council.

Algerian officials have repeatedly said their government did plenty to protect the United Nations.

The Algiers attack was the deadliest single act of aggression against U.N. staff and facilities since August 2003, when the world body's headquarters in Baghdad was hit by a truck laden with explosives, killing 22 people including the top U.N. envoy in Iraq.

In its 103-page report Tuesday, the panel headed by veteran Algerian diplomat and U.N. troubleshooter Lakhdar Brahimi cited widespread problems in the U.N.'s Department of Safety and Security headed by Veness.

"The gaps and weaknesses include: leadership and accountability, and internal management and oversight," it said.

In particular, the report said that:

—Since 1992, 270 U.N. civilian staff — 80 percent of them locally hired — and 2,468 uniformed personnel have been killed by "malicious acts, including murder, bombings, land mines and hijacking."

—U.N. security in Algiers, as in other countries, was coordinated with the government mainly through a single point of contact, which limited safety discussions.

—Often the most serious risks are in the countries with the fewest resources for protecting U.N. staff.

—An important issue for the U.N. to address "is why a significant and growing part of the public no longer perceives the U.N. as impartial and neutral."