Updated

With copper prices at a near record, thieves across the country have been stealing copper wiring from power lines, construction sites and warehouses. Now federal officials say thieves are targeting power substations and even a locked recycling yard at a nuclear lab.

The Energy Department's inspector general reports a "troubling increase" in copper thefts from federal sites, including national research labs, generating stations and a plant where nuclear weapons are dismantled and stored.

An estimated total of $500,000 to $750,000 worth of copper has been stolen from DOE sites in the past three years, Inspector General Gregory Friedman said.

Thefts have ranged from small amounts to about 30,000 pounds of copper stolen from the Los Alamos National Laboratory in New Mexico. In Texas, hundreds of pounds of copper were stolen from the Pantex plant near Amarillo, where nuclear weapons are stored and dismantled.

Friedman said DOE officials need to improve security, especially at recycling facilities and remote substations.

In many instances, stolen copper "had not been secured in any way," Friedman wrote in a three-page letter Thursday. Some DOE sites had only minimal access controls to areas where copper is stored, Friedman said.

In the Los Alamos case, about 30,000 pounds of copper — worth an estimated $120,000 — was stolen from a fenced facility that is locked after hours. Four contractor employees were convicted in the case.

In Texas, an electrician apprentice was convicted of stealing more than 100 pounds of copper from a recycling bin at the Pantex plant. A former supervisor was also convicted in the case.

Bryan Jacobs, executive director of the Coalition Against Copper Theft, called the crimes a national security issue. The coalition, which includes power companies, electric contractors and railroads, wants Congress to pass legislation setting minimal requirements for scrap yards that deal in copper and other metals.

Copper was selling for nearly $4 a pound Thursday, more than double the price in early 2009.