Failure at the Los Alamos National Laboratory to follow security procedures is widespread and the highly secretive nuclear facility lacks an effective system to prevent employees from removing classified material, Energy Secretary Spencer Abraham said in a toughly worded statement yesterday that threatened firings and left open the possibility of a criminal investigation.

Missing computer disks, classified information sent out via e-mail and an accident involving a summer intern injured in the eye by a laser forced Los Alamos to stop nearly all of its operations over the weekend, including weapons research and field testing, as a major investigation into serious security breaches and accidents got underway.

The latest incidents at the New Mexico lab, which has been plagued by security problems for a decade, are being treated as accidental but that could change, said Rep. Joe Barton (R-Tex.), chairman of the House Energy and Commerce Committee.

"This may turn into intentional disregard for the rules or an espionage investigation led by the FBI," Barton said after returning from a tour of the laboratory Monday with Deputy Energy Secretary Kyle McSlarrow and Rep. Diana DeGette (D-Colo.), who serves on Barton's committee.

Los Alamos, established in 1943 to build the atomic bomb, conducts some of the nation's most sensitive scientific research and plays a key role in maintaining the country's nuclear stockpile. Scientists at Los Alamos work in a wide variety of disciplines, including nuclear weapons development, advanced military systems and new technologies used in homeland security.

Abraham ordered additional security personnel to Los Alamos and said McSlarrow and Linton F. Brooks, director of the National Nuclear Security Administration, would "coordinate with other federal agencies associated with the work of Los Alamos, as well as with the FBI, to keep them fully informed of this investigation."

In his statement, Abraham said his deputy and Brooks, who are overseeing the nascent investigation, were already "concerned that some within the laboratory work force fail to understand the seriousness of the situation."

"This clearly illustrates the need both for immediate, effective and permanent corrective action and for meaningful administrative and disciplinary action at an appropriate time," the statement continued.

DeGette said laboratory director George "Pete" Nanos "intends to fire some people and to change the culture there."

A senior official in the Energy Department, who spoke on the condition of anonymity, confirmed that firings were being considered along with revoking security clearances held by some scientists.

The laboratory reported two weeks ago that two computer disks containing secret documents were missing. This week, it acknowledged that classified information was sent out over insecure e-mail more than a dozen times and that a 20-year-old woman interning over the summer was seriously injured during a laser experiment.

In response, Nanos suspended much of the work done by about 12,000 employees last Friday, and on Monday the shutdown was extended to include work on plutonium research at the lab's field-test site in Nevada. Several classified projects deemed essential for national security will continue to operate.

Those involved in the investigation have said attention is focusing on a small group of Los Alamos veterans who are not abiding by laboratory rules. Nanos referred last week to "cowboys" who do not properly handle classified material. "I don't care how many people I have to fire to make it stop," he said. "If you think the rules are silly, if you think compliance is a joke, please resign now and save me the trouble."

Kevin Roark, spokesman for Los Alamos, said that during the shutdown, "supervisors are going to have one-on-one meetings with every single employee to explain the rules and expectations at Los Alamos.

"If we get the sense that someone here isn't willing to buy into that, then they should consider other places of work."

Abraham said all classified operations dealing with removable material will be stopped until new security arrangements are in place. Other areas may resume operations sooner.

"Given the very broad nature of the classified activities underway at the lab and likely differences in the ability of some divisions to implement security modifications more quickly than others," he said, "I expect the restart of the various operations to take place in stages rather than all at once."

Los Alamos has faced a growing list of security lapses, espionage charges and fraud allegations in the past decade.

In 2000, two disk drives were lost and then turned up behind a copy machine. In November 2002, the laboratory faced charges of equipment theft and purchasing fraud and last December, an inventory could not account for 10 computer disks containing information about the nuclear weapons program. Four Los Alamos workers also were contaminated from exposure to plutonium last year.

The University of California, which has been the sole manager of Los Alamos for six decades, has said it may not bid for the management contract next year.