Spanish nuclear experts have found several hundred pounds of depleted uranium in the wreckage of two jumbo jets that crashed in the Canary Islands last March, killing 577 persons, Madrid officials said yesterday.

A Spanish government spokesman said the material has a low level of radioactivity and was not dangerous.

The March 27 collision of a Pan Am 747 and a Duch KLM jumbo jet on a foggy runway at Santa Cruz de Tenerife was the worst disaster in aviation history.

John Newland, a spokesman for the Boeing Co. in Seattle, which makes 747s, said about 950 pounds of depleted uranium are added to the tail of every 747 to counterbalance the upper rudder and outer elevators, which help the planes go up or down.

Newland said the depleted uranium, which is technically caled U-238 and has the fissionable uranium (U-235) removed, could not affect instruments of radio transmissions.

Robert Huber, a spokesman for the Federal Aviation Administration in Los Angeles, said manufacturers have used depleted uranium as counterbalance weights in large aircraft for the last 17 years.

Fred Farrar, an FAA spokesman here, said, "Uranium in 747s and other airplanes is ued with the FAA's knowledge and approval. It's even in the Lockheed Jetstar (the small business jet) that the FAA administrator uses." The material was chosen, he said, because "a small amount is awfully heavy." A handful of U-238 weights about 25 pounds.

Farrar said the depleted uranium is plated with nickel and cadmium to prevent oxidation before it is inserted in the 747 tails.

"There is no radiation hazard to passengers," he said. An article in the Tenerife newspaper EI Dia Thursday said more than 600 pounds of uranium were found in the wreckage, that for several months it was in a local junk and scrap-metal shop, and that 33 pounds of it later came into the possession of a jeweler who thought it was white gold.

Farrar said the article caused some concern in Spain because of an implication that the uranium is "hot" and that it might have been part of the plane's cargo. It was neither, he said.