COLUMBIA, S.C. (AP) - Work has stopped on closing two high-level nuclear waste tanks at the Savannah River Site following a federal judge's ruling earlier this month.

A federal judge in Washington state ruled earlier this month that the department violated the law when it granted itself the authority to reclassify some of the millions of gallons of hazardous, highly radioactive wastes stored in tanks in South Carolina, Washington and Idaho.

The judge overturned a regulation the Energy Department claimed allowed it to reclassify highly radioactive waste so it would not have to be permanently removed.

"We're still trying to figure out everything that the ruling impacts," Department of Energy spokesman Jim Giusti, who works out of the SRS office near Aiken, said Thursday.

At SRS there are 37 million gallons of high-level waste in 49 tanks. The site has already closed two tanks with some waste left in the tanks, but halted work on two tanks they were planning to close, Giusti said.

SRS had developed an aggressive accelerated plan to reduce the cost of cleanup by $12 billion and shorten the schedule by 20 years.

"The ruling has really thrown the accelerated plans at SRS in disarray," Giusti said.

Workers trying to close the high-level waste tanks at the former nuclear weapons complex have shifted to other assignments, Giusti said.

The government hasn't figured the potential cost and delays of cleanup "but we're probably talking about additional billions of dollars and additional decades to finish the cleanup," Energy Department spokesman Rick Ford said.

The agency's lawyers are "keeping their options open" and have not yet decided whether to appeal, said Energy Department spokesman Joe Davis in Washington, D.C.

The Defense Waste Processing Facility at SRS, which converts the most dangerous contents of the tanks into glass logs, is scheduled to make as many as 6,000 logs for eventual storage at Yucca Mountain, Nev. If the entire contents of the tanks have to be handled in that fashion, Ford said it could mean 120,000 glass logs and the possible construction of an additional processing facility.

Geoffrey Fettus, an attorney for the Natural Resources Defense Council, which sued the DOE, said the council is examining its options concerning the two Savannah River tanks already filled with concrete.

"For (the Energy Department) to say this is going to slow down cleanup is ridiculous," Fettus said. "The law says get all the waste out of the tanks. We think this goes to the completeness of cleanup, not the pace."