WASHINGTON -- Facing mounting criticism, Rep. Jim Gibbons on Thursday defended legislation that would resume government sales of federal land to mining interests.

The Nevada Republican last month inserted the mining law change into a $50 billion budget reconciliation bill awaiting House approval.

Mining advocates welcomed the bill, which would end a nine-year ban on land patenting, sales to mining companies and prospectors.

But since then, Democrats and environmental groups have slammed the bill, saying it would open 5.5 million acres of public land across the West, including national parks and even property in the Las Vegas Valley that is controlled by a separate land sale law.

Gibbons said his efforts "have been misconstrued and misinterpreted. The claim that this is a public land giveaway is dishonest and false."

Gibbons, a geologist, said his bill would limit land sales to individuals who would mine the land and could prove the land contained an "economic viable resource."

He said sales in national parks and other protected areas would be banned.

"You cannot go in and stake a false claim. That's illegal and in violation of the law," Gibbons said.

But critics say there are loopholes. They say the proposal would, for instance, allow developers to stake a mining claim, obtain property and then build ski lodges or housing developments.

"It could launch one of the single biggest fire sales of federal land in history," said John Leshy, a former solicitor at the Department of Interior in the Clinton administration.

One analysis critics circulated in Congress on Thursday further suggested that the bill could circumvent federal land sales in Clark County carried out under the Southern Nevada Public Land Management Act.

The 1998 law preserved an estimated 150 mineral claims in the valley, but critics said Gibbons' bill would open millions of acres bordering those claims. Many of those lands are slated for future sales by auction under the Southern Nevada land law, a congressional official said.

"Gibbons' mining law reform would allow land speculators to claim and patent (privatize) unlimited amounts of land within the Las Vegas Valley at rock-bottom prices as long as some part of the lands are contiguous to an old mining claim that existed before the passage of SNPLMA," the analysis stated.

Gibbons called the interpretation "absolutely false."

The bill would impose a $1,000-an-acre fee or fair market value price, whichever is greater, on land sales to mining interests. The new fee is much higher than the $2.50 per acre the government had charged before sales were suspended in 1996.

Democrats say the revised fee, though higher than before, still fails to account for the profits mining companies would make from the minerals beneath the ground.

"This provision would allow the sale of potentially mineral-rich public lands for the mere cost of the surface estate, completely ignoring the value to the underlying mineral estate," Rep. Nick Rahall, D-W.Va., said in a statement.

The bill also would convey 7,000 acres of Bureau of Land Management property in Pershing County to the Rochester Coeur Inc., a Lovelock mining outfit that wants to turn its exhausted mining operation into a money-making landfill.

Gibbons has said the bill would require Rochester Coeur to pay $7 million, far more than a recent $68-per-acre appraisal.