SANTA FE, N.M. - The meth addict who was staying in a mobile home where police discovered classified information from Los Alamos National Laboratory says he knows nothing about the material.

"I was basically at the wrong place at the wrong time. … This whole thing is a real mess," Justin Stone told The Associated Press in a telephone interview from jail.

"I don't know who to sell that kind of information to. I don't know who would be interested in that kind of stuff," said Stone, 20, who is jailed on drug and probation violation charges.

Stone was renting a room in the home owned by Jessica Quintana, who previously worked for a lab subcontractor, Information Assets Management.

Quintana, 22, has not been charged in the case.

The FBI, which is investigating the security breach, is reviewing three portable computer storage drives that were removed from the home during a drug bust last week.

Lab Director Michael Anastasio told employees Thursday that while he couldn't discuss details, "I can confirm that classified material was found in her residence," according to a statement released by the lab Friday.

He also ordered lab officials to immediately take steps to improve security, including making sure that classified materials can't be downloaded to unauthorized devices.

"I had no idea what was on those jump disks," said Stone, a high school dropout who described himself as addicted to methamphetamine, which he said he has used since he was about 14.

Stone acknowledged that one of the three USB flash drives was his. He said he got it in trade for $20 worth of meth from a man who had "no relationship to the lab whatsoever."

Stone said the FBI told him the flash drive, which he had intended to store music on, contained pornography.

Stone said he had no knowledge of what was on the other two flash drives. He said Quintana, from whom he had been renting a room for about three weeks, had never talked about her lab work with him.

"I'm freaked out. I'm still really scared about the whole thing. I had all this information under the roof that I was living in, and all of a sudden the FBI is interrogating me," Stone said.

The security measures announced by Anastasio also include enhanced search procedures; a review of all classified scanning activities; a review of security requirements for lab subcontractors; a review of policies for escorting workers and visitors and for the operation of vault-type rooms; and "robust training and communications" to be sure that security requirements are understood.

The measures were to begin immediately and be completed by the end of the next week.

"Let me reiterate that this is very serious, and by working together we can get through it," Anastasio said in the statement.

The Department of Energy facility, which has been plagued by security lapses in recent years, has been operated since June by a team made up of Bechtel National, the University of California - which had run the lab since 1943 - BWX Technologies and Washington Group International.

"I am shocked that in this day and age you can still have memory sticks," said Pete Stockton, senior investigator at the Project on Government Oversight, a Washington, D.C.-based watchdog group. "This is how many years after Wen Ho Lee?"

Lee, a former lab scientist, pleaded guilty in 2000 to a single count of mishandling nuclear secrets, He had transferred information needed to design computer simulations for nuclear explosions to pocket-size portable computer tapes so he could have backup copies. He said he later threw away the computer tapes in a lab trash bin.