Efforts are underway to find more than two tons of natural uranium reported missing from supplies held in Libya, the International Atomic Energy Agency confirmed Wednesday.

A spokesman from the nuclear watchdog told CNN in an email that “approximately 2.5 tons of natural uranium” contained in 10 drums were found to be missing during an inspection on March 14.

“Agency safeguards inspectors found that 10 drums containing approximately 2.5 tons of natural uranium in the form of uranium ore concentrate were not present as previously declared at a location in the State of Libya,” the IAEA said in its statement.

IAEA Director General Rafael Mariano Grossi has informed the agency’s member states and officials are working to find out what happened to the uranium and where it is now, the statement added.