The Interior Department is preparing to put into effect a new federal regulation that, according to several National Park Service officials, will expand the rights of coal companies to develop strip mines on 3.7 million acres of private property within national parks.

Elsewhere in the massive domain supervised by Interior Secretary James G. Watt, officials recently began processing applications for oil and gas leases on as many as 1 million acres of land in national wildlife refuges.

Such leasing is being considered for the first time in 25 years under a new interpretation of rules issued by the Interior Department's Board of Land Appeals.

And in the U.S. Fish and Wildlife Service, which manages 90 million acres of public land, officials are carrying out new orders to expand the "economic uses" such as haying, grazing, timber cutting, oil and gas extraction and hunting and fishing in wildlife refuges, according to a recent directive. These and other significant policy changes were being carried out yesterday at the department under little public scrutiny as politicians and the national media focused on the controversy surrounding Watt's recent remark characterizing members of an advisory panel as "a black, . . . a woman, two Jews and a cripple."

"We're conducting business as usual," a spokesman said. "Life goes on here. There are no changes."

Watt's aides and his defenders in Congress continued to assert yesterday that the controversial secretary should be judged on his record at the Interior Department rather than on what he says.

Controversy about Watt began almost immediately after he took office as he directed what he called "massive changes" in management of the vast federal estate: wilderness areas, national parks, wildlife refuges, wild and scenic rivers and more than 300 million acres of grazing and mining lands.

The Office of Surface Mining, which regulates strip mining, was a prime target for many such changes, particularly for Watt's campaign to rewrite what he called "costly, burdensome and counterproductive" federal regulations.

One new regulation, scheduled to take effect Oct. 14, defines special cases in which companies can establish rights to strip mine privately owned coal deposits within the boundaries of national parks, national forests, wildlife refuges and other protected areas.

The regulation says state officials must decide whether a company has the right to mine in federally protected areas within the state's borders.

The right must be recognized, according to the rule, if a prohibition on mining would lead to an unconstitutional "taking" of private-property rights to a coal deposit.

The rule prohibits mining on federal lands within national parks, refuges, trails, wilderness areas and other protected areas and commits the interior secretary to "employ the full range of his legal capabilities" to acquire or condemn mining rights on these lands.

The prohibition does not extend, however, to private lands within these protected areas. According to the National Park Service, 3.7 million acres of these lands in 55 units of the park system are believed to contain coal deposits.

Included are 11,000 acres of Chaco Culture National Historic Park in New Mexico.

The new regulation says only that the park service will be notified if anyone applies for permits to mine in these areas and can "take any action at its disposal, including possible acquisition of the property" to prevent mining.

National Park Service Director Russell E. Dickenson said yesterday that the service would "move promptly" to buy or, if necessary, condemn any private property threatened with strip mining within a park's boundaries. He said he has Watt's "complete support" on the matter.

Interior Department officials said their revised rule is as strong as it can be without violating the Constitution and private-property rights, and a spokesman for Watt said: "We will not allow this regulation to be a vehicle for damaging the parks' resources."

But environmentalists and several Interior Department officials, all of whom insisted on anonymity, said the department has significantly expanded the rights of private mining companies within protected areas, specifically the 3.7 million acres of private land within park boundaries.

The officials noted that Watt has imposed a near-moratorium on buying new land for the national park system, including pockets of private land within parks.

The most threatened of the park units, according to the park service, is New River Gorge National River in West Virginia, 62,000 acres of coal-rich lands along the rugged, whitewater New river.

The park was authorized by Congress in 1978, and more than 55,000 acres remain to be purchased.

The Interior Department estimated in 1981 that more than 3.6 million tons of coal lie under these lands.

An official of the Office of Surface Mining who also insisted on anonymity said one purpose of the new rule is that "Watt wanted to allow for a situation in which mining might not truly be an incompatible use" of a national park.

He cited in particular New River Gorge, historically a site of mining activity.

In adopting the regulation, the Interior Department dismissed complaints by officials of the nation's No. 1 coal-producing state, Kentucky, who warned that states invoking the regulation in an effort to outlaw mining in parks will be subject to expensive lawsuits by mining companies claiming that the states effectively had condemned their property.

"Presumably, Congress did not intend to have those prohibitions decided upon by an interested party," wrote Carl Breeding, general counsel to Kentucky's division of natural resources.

The Interior Department also discarded an earlier version of the rule that was published last year as one of several options and that would have "maximized" protection of parks from strip mining, according to a National Park Service document.

That option was similar to a rule written by the Carter administration and later struck down as too broad by a federal judge.

It essentially banned mining in national parks by requiring companies to have purchased the coal and obtained permits to mine it by Aug. 3, 1977, when the federal strip-mining control law was enacted.

In his opinion striking down the rule, the judge suggested that the regulation could pass legal muster with only minor changes, such as requiring only a "good-faith effort" by companies in obtaining permits by the cutoff date.

An Interior Department official familiar with the rule said this proposal was discarded as "unworkable."

National Wildlife Federation attorney Norman Dean said yesterday that the group plans to sue in an effort to invalidate the rule as "flatly inconsistent with the federal strip mining law, whose legislative history makes it crystal clear that the secretary is to provide maximum possible protection for national parks."