RENO, Nev. - Nevada's attorney general is making another bid for a court order blocking shipments of weapons-grade plutonium to a site near Las Vegas, declaring Thursday that the U.S. government's assurances no more of the radioactive material is Nevada-bound "aren't worth the paper they're written on."

Attorney General Aaron Ford filed notice earlier this week that the state will appeal to the 9th U.S. Circuit Court of Appeals after a federal judge in Reno refused to grant an earlier request for an order prohibiting shipments.

He filed a new motion in U.S. District Court in Reno on Thursday seeking a preliminary injunction to block the arrival of any more plutonium until the San Francisco-based appellate court rules.

The Energy Department disclosed for the first time on Jan. 30 that it secretly trucked 1,000 pounds (453 kilograms) of the highly radioactive material to the site sometime before November, when the state first filed a lawsuit seeking to ban the shipments from South Carolina.

The department said it doesn't intend to ship any more of the material from its Savannah River site to Nevada.

But Ford said in earlier court documents that lawyers representing the DOE had told Nevada's lawyers as recently as last month that no shipments would occur until at least the end of January, only to learn it had been shipped months earlier.

"When the Department of Energy takes unilateral action to ship dangerous material to Nevada, it robs the state of our ability to prepare for the risks associated with transporting and storing plutonium," Ford said Thursday.

"Frankly, the Department of Energy has lost all credibility and trust, and its assurances that it will not ship any plutonium in the future aren't worth the paper they're written on," he said.

DOE officials said in revealing the previous shipment last week that they had to keep it secret until recently for national security reasons. They insist appropriate notice was provided in August when the DOE approved plans to temporarily store plutonium in Nevada to meet a court-ordered deadline to remove it from South Carolina by Jan. 1, 2020.

"DOE was as transparent about this movement as operational security would permit," DOE said in a statement Thursday night.

"The state of Nevada's latest motion to stop all plutonium shipments into the state puts at risk not only important ongoing national security missions, but also the livelihood of the nearly 3,000 Nevadans who play an incredibly important role in ensuring those missions are executed," the department said in an email to the AP.

The state fears an accident could permanently harm an area home to 2.2 million residents and host to more than 40 million tourists annually. Experts testifying on behalf of Nevada at a hearing on Jan. 17 said the material likely would have to pass directly through Las Vegas on the way to the Nevada Nuclear National Security Site about 70 miles (113 kilometres) north of the city.

Nevada Gov. Steve Sisolak said in a letter to Energy Secretary Rick Perry on Wednesday that his "callous disregard" for Nevada's interests has endangered residents and "destroyed any semblance of trust."

He said Thursday the new motion is intended "to prevent the Department from pulling this despicable stunt again while the Ninth Circuit considers our appeal."

Nevada argues DOE is relying on outdated environmental reviews to justify the shipments and should have to conduct further studies required by the National Environmental Policy Act to consider the population growth and increased traffic in the Las Vegas area over the past decade. It says DOE intends to leave the material in shipping containers not intended for storage until it plans to transfer the materials elsewhere.

DOE said earlier it wanted to temporarily store the material at the Nevada site and the government's Pantex Plant in Texas, two facilities that already handle and process plutonium. The department says it would be sent by 2027 to the Los Alamos National Laboratory in New Mexico or an unnamed other facility.

News from © The Associated Press, 2019