WASHINGTON —  A judge ordered the Interior Department to disconnect from the Internet all computer equipment holding data related to trust accounts it manages for American Indians, a decision that could cripple large sections of the agency's computer network.

In a 205-page opinion declaring the department's computer security "disorganized and broken," U.S. District Judge Royce Lamberth on Thursday said the order applies to all networks with access to trust data — from servers to BlackBerrys (search) — except what is necessary to protect from fire or threats to life, property or national security.

Lamberth wrote that he expected the Interior Department to quickly try to block his ruling.

However, he added, "Failure to take immediate action in this regard risks the complete destruction of these Indians' trust interests in the long term. Perhaps today's order will help illuminate the pervasive problems that continue to plague Interior's (computer) security environment."

Interior Department (search) officials scrambled to determine what systems it applies to.

Interior spokesman John Wright said the new order could affect as many as 6,000 computers that directly contain Indian trust data and "an undetermined number" of other computers with indirect access.

"Based on our initial review of the order, it will adversely impact our ability to conduct program activities that benefit Native Americans as well as other parts of the Department of Interior mission," Wright said. "This includes our ability to collect, process and distribute rents and royalty payments for both Indian beneficiaries and the federal government."

Whether the department has been able to keep trust data secure is a key issue in an almost 10-year-old court battle in which thousands of Indians accuse the government of cheating them of more than $100 billion by mismanaging oil, gas, timber and other royalties on their land dating back to 1887.

The Bureau of Indian Affairs and other Indian-related agencies with Interior have been off-line since Lamberth's 2001 order blocking access to trust data.

In other past decisions, Lamberth lambasted the department for its treatment of the Indians' accounts, holding both Interior Secretary Gale Norton (search) and her Clinton-administration predecessor Bruce Babbitt in contempt. The ruling against Norton was later overturned.

After his last decision in July, the department took the rare step of asking to have Lamberth removed from the case. The appeals court has not acted on the request.

In the past three years, the department has invested more than $100 million in computer security.

But in his order Thursday, Lamberth wrote that investigators testified they would give the department's computer security an 'F' grade or "one notch lower than an 'F' ... a 'G."'

During a 59-day evidentiary hearing this summer, computer experts, including the department's inspector general, testified that during security tests, investigators were frequently able to hack into several systems, including those that could contain Indian trust data.

Lamberth's order gives the department 20 days to identify each computer system that remains connected to protect against fires or threat to life, property or national security. It also gives the agency an opportunity to prove it has addressed the security concerns.