The uranium materials and the chemical agent in Libya remained secure, the U.S. State Department said on Thursday.

"All sensitive elements of Libya's nuclear program, including everything that Libya received from the A.Q. Khan network, were removed in early 2004," said State Department spokesperson Victoria Nuland. "The last of the highly enriched uranium, the bomb-making fuel, was removed from Libya in 2009."

"Libya does have a supply of yellow cake. It is at the Tajoura nuclear research facility. It is safeguarded there," she said, asserting it was "secure" and Libya did not have the means right now to "turn yellow cake into anything dangerous."

In terms of the mustard agent that Gaddafi had, Nuland said that it was now stored at the Waddan Ammunition Reservation.

"It is inside massive steel containers within heavy bunkers. These bunkers were sealed by the Organization for the Prohibition of Chemical Weapons, the OPCW," she said.

"Our judgment is that they remain secure," said Nuland, adding that the U.S. was able to monitor its security with national technical means.

Nuland added that U.S. envoy Chris Stevens, in the last couple of days, had been in contact with Libyan opposition leaders to talk about their readiness to take physical control of the facilities storing the chemical weapons and the yellow cake.