Two dozen industry and green groups submitted their suggestions on the proposal to the Interior Department before this week's deadline for public comments.

The department's Office of Surface Mining proposed in May that mining companies - which now are responsible for short-term clean-up costs - should also pay for unexpected "long-term" acid or toxic mine drainage that can seep into area water supplies.

Federal mining regulators asked for suggestions to help determine how many years a company should have to cover clean-up costs for an abandoned project as well as ways to pay collateral using alternative sources in addition to bonds.

The proposal is being watched by some green groups as a test of the Bush administration's commitment to environmental protection. The White House has been criticized by some groups for being too eager to ease costly rules opposed by mining, logging, energy and manufacturing companies.

U.S. mining companies, which have sought to ease bond requirements because of the souring economy, said the Interior Department lacks authority to retroactively increase bonding requirements if pollution levels are more severe than first estimated.

In a 29-page submission, the National Mining Association said boosting financial clean-up costs "after a permittee has met the standards" is fundamentally illegal. Such a move could force many companies, which are in financial trouble from weak metals prices, into bankruptcy.

"Such liability would adversely affect many mining operations and may result in operations shutting down, which would completely defeat the purpose of the policy objective," the trade association said.

ENVIRONMENTAL PROTECTION

Several green groups wrote that projects that could result in either short or long-term damage to the environment should not be allowed to move forward.

The Citizens Coal Council said in a letter that by increasing clean-up requirements, the government is admitting pollution discharge from coal mines is a problem rather than forcing the industry to prevent it, which the mine operator must do in order to receive a permit.

The advocacy group estimated the cost of cleaning abandoned U.S. mines at more than $6 billion.

"I urge you to adopt enforcement guidelines that can impose monetary fines that exceed the actual cleanup costs," Michael Stieber, a Boulder, Colorado environmental supporter wrote.

"Industry must be made to understand that failure to operate in an environmentally safe manner is not cheaper than paying a fine."

Another federal agency also weighed in on the proposal.

The U.S. Fish and Wildlife Service, a division of the Interior Department, said that while an initial high bond level may be necessary, "once a bond has been paid for a particular permitting action, a mining applicant's obligations are fulfilled."