A federal judge here has scuttled an Interior Department rule that could have opened more than 3.7 million acres within national parks to strip mining.

In a decision filed Friday, U.S. District Court Judge Thomas A. Tierney said the department violated administrative procedures in September 1983 when it issued a new definition of "valid existing rights" that would have made it easier for companies to mine privately owned coal deposits within the boundaries of federal parks, forests, wildlife refuges and other protected areas.

The rule, issued under former secretary James G. Watt as part of a major overhaul of strip-mining regulations, caused a furor among conservation groups and state officials. The new definition, for example, could have opened more than 55,000 acres of the 62,000-acre New River Gorge National River in West Virginia to strip mining.

Though Interior officials said that the National Park Service would have the option of buying private property threatened with strip mining, the rule was issued when the administration had imposed a near-moratorium on land purchases, including private parcels within park boundaries.

The decision is not likely to end the controversy over mining rights in protected lands, however. Tierney ruled not on the legality of the new definition but on the process by which it was reached. The definition was so different from the department's original proposals that it required a separate comment period, he ruled.

"We're back to square one, but hopefully with an Interior secretary who is more sensitive to the need to protect national parks," said Norman Dean, attorney for the National Wildlife Federation, which had joined other conservation groups in challenging the rule.