It is still not known how much information was stolen. But sources inside the bank confirm that servers in the institution's highly-restricted treasury unit were deeply penetrated with spy software last April.

In total, at least six major intrusions — two of them using the same group of IP addresses originating from China — have been detected at the World Bank since the summer of 2007, with the most recent breach occurring just last month.

The crisis comes at an awkward moment for World Bank president Robert Zoellick, who runs the world's largest and most influential anti-poverty agency, which doles out $25 billion a year, and whose board represents 185 member nations. This weekend, the bank holds its annual series of meetings in Washington — and just in advance of those sessions, Zoellick called for a radical revamping of multilateral organizations in light of the global economic meltdown.

Zoellick is positioning himself and the bank as an institution that can help chart a new path toward global financial stability. But that reputation, more than ever, depends on the bank's stable information infrastructure.

In reality, the situation is serious enough that federal investigators have been called in. "We're not talking about hackers playing games or messing up our website," insists a senior member of the bank's IT department at its Washington headquarters. "It's about the FBI coming last summer and saying, 'You should take a look at your systems because we think something weird is going on.' It's about the intruders knowing what information they wanted — and getting to it whenever they wanted to. They took our existing data stores and organized them in a way that they could be easily accessed at will."

In plainspeak: "They had access to everything," says the source. "They had the keys to every room at the bank. And we can't say whether they still do or don't until we fully and openly address what's happening here."

The data raids are not a matter of stealing inconsequential bits and bytes. The World Bank's data center is literally a treasure trove of vital financial information from around the globe. As a clearinghouse for financial data from both governments and companies, the bank's computers could provide intruders with both a financial and intelligence gold mine — from inside information on bids and contracts to the minutes of confidential board meetings.

IMF officials clamped down on their computer systems on November 7, after they discovered spyware that was quickly spreading through the institution's high-security computer system. Spyware is software that is secretly installed on a computer to intercept information or take control of the system.

The IMF's network link to the World Bank, the world's largest anti-poverty agency, was also temporarily severed, a move that IMF spokesman Bill Murray described as a "precaution."

But IMF officials strenuously deny that any lockdown of its computers took place, and insist that no important or sensitive financial information had been affected.

"There was no lockdown as far as I'm aware" says Murray. "I'm not aware of any major breaches, but enhanced security measures have been taken."

Prodded further as to the discovery of spyware, Murray responded: "As part of our ongoing [security] regime, we've had a scan of Fund personal computers and laptops and we found some workstations that did have malicious software, but absolutely no evidence that any sensitive information or systems were breached."

As FOX News reported on October 10, the World Bank itself suffered a series of cyber-attacks starting in the summer of 2007, both at headquarters and at other offices around the world. The World Bank strenuously denies that the intrusions took place, and none of the bank's 24 board members contacted by FOX News would discuss the matter. But sources told FOX News that at least one of those breaches also involved spyware, penetrating the World Bank's ultra-sensitive Treasury unit, which manages a $75 billion portfolio for itself and for several nations

The World Bank, however, did not take the dramatic step of shutting down all its computer systems to eliminate any spyware. Security experts say it is possible that the bank may have inadvertently infected the IMF — simply by sharing some wires in the IMF's sublet building. Moreover, as FOX News reported last month, hundreds of workers previously employed by an Indian contractor that is barred from Bank contracting work on security grounds still work at the institution, either as regular staffers or as employees of other contractors.