ALBUQUERQUE, N.M. (AP) - The federal government has finished moving its most sensitive weapons-grade nuclear material from a Los Alamos National Laboratory technical area to more secure sites.

The weapons-grade plutonium and highly enriched uranium is no longer within Technical Area 18 at the lab, which has been rocked by fiscal and security lapses in recent years.

The move was driven by changing threats following the Sept. 11, 2001, terrorist attacks on the East Coast and efforts to save money, Kevin Roark, a lab spokesman, said Thursday.

"Over the years it's become increasingly more expensive to have secure areas," he said.

The material has been moved to the Nevada Test Site, the Y-12 National Security Complex at Oak Ridge, Tenn., and the lab's Technical Area 55, the National Nuclear Security Administration said.

"It increases our comfort level for security margins," Roark said.

The material taken to Technical Area 55 eventually will be moved to the Nevada Test Site, said Bryan Wilkes, NNSA director of public affairs in Washington, D.C.

The material taken to Y-12 is considered surplus highly enriched uranium and will remain at that site, he said.

Similar bomb-grade material is at other sites, including Lawrence Livermore National Laboratory in Northern California and the Pantex facility at Amarillo, Texas, Wilkes said.

The project to move the material from Technical Area 18 began in September 2004 and was completed almost on time despite a seven-month stand-down at the lab, the NNSA said.

The lab was virtually shut down in July 2004 after reports that two classified computer disks had disappeared. An investigation later determined they never existed. Some of the lab's formal activities did not resume until February.

The project to move the nuclear material was targeted for completion on Sept. 30 and was wrapped up Oct. 26, said Roark and NNSA officials.

The Project on Government Oversight - a nonpartisan government watchdog group based in Washington, D.C. - praised the move but questioned why it took so long.

"They're getting the job done five years after the secretary of energy ordered it to be done," said Beth Daley, the group's director of communications.

The Los Alamos lab was founded during World War II's Manhattan Project to develop the first atomic bomb, and Technical Area 18 dates back to that time.

The area originally was used to conduct criticality experiments - "basically figuring out how much nuclear material you need to reach critical mass, and reaching critical mass is essential to triggering a nuclear detonation," Roark said.

"There's still very important work at TA-18 in nonproliferation, in training of nuclear inspectors and nuclear safety work continues," he said.

On the Net:

Los Alamos National Laboratory: http://www.lanl.gov/

National Nuclear Security Administration: http://www.nnsa.doe.gov/

Project on Government Oversight: http://www.pogo.org/