The site of India's recent nuclear tests

(CNN) -- The U.S. Department of Commerce approved more than $151 million worth of "dual use" technology for export to India last year, including material and technology that can be used in nuclear weapons programs, CNN has learned.

A long-standing U.S. policy prevents shipments of nuclear weapons technology to India. But products with civilian uses could sometimes gain approval from the Commerce Department.

One such product is the space-age metal beryllium. Last year, the BrushWellman company of Cleveland sent 64 kilograms of the metal to India for $99,000.

CNN's Aram Roston reports 3 min. 15 sec VXtreme video

The Indian importer promised to process the metal into satellite parts and send them back to the United States.

But Hughes, the U.S. customer for those satellite parts, said it received only of fraction of what was ordered. And according to nuclear experts, only 2 to 4 kilograms of beryllium would be needed for a nuclear bomb.

Adding beryllium to nuclear weapons increases the force of an atomic blast, experts say

Commerce Department spokesperson Roger Majak said several agencies reviewed the sale of beryllium, agreed it was legitimate and approved it. But he added, "Under the new policy, its likely we will not sell any beryllium to India."

Gary Millhollin of the Wisconsin Project, a nuclear watchdog group, said beryllium should not be sent to India. The metal can be used to make nuclear weapons smaller, lighter and more powerful.

"It makes the yield, that is, the explosive force of the nuclear weapon, much greater if you use a sphere of beryllium around the uranium core, because it increases the number of fission reactions," Millhollin said.

Another dual use product that went to India was the advanced oscilloscope, which can be used to read the force and speed of a nuclear test. CNN has learned that $669,000 worth of advanced oscilloscopes went to India.

Millhollin said that without such devices a nuclear test explosion is useless. "I think it's very likely that these oscilloscopes were used to process the data from India's nuclear tests."

India exploded five nuclear devices in May, raising tensions with Pakistan, which retaliated by carrying out its own tests.

Correspondent Aram Roston contributed to this report.