Interior Secretary James Watt promised yesterday to ease the way for mining companies to hunt minerals in wilderness areas, calling the controversial shift an important part of a new strategic minerals policy.

Watt told the House Interior subcommittee on mines that existing law permitting exploration in wilderness lands "has not been followed as aggressively as I think it should be."

Previous administrations have not allowed the virgin forests and mountainside to be touched, but "we will allow the acts of Congress to be followed," Watt said. He added he would consider extending the 1984 deadline that was set for such exploration in the Wilderness Act of 1964.

Tim Mahoney of the Sierra Club responded in an interview that most lands were thoroughly checked for possible mineral deposits before being included in the wilderness category, which prohibits roads, construction, surface mining and other forms of development. "The minerals people were very successful in excluding minerals areas from wilderness designation," he said. "There really aren't many [wilderness] areas where they want to go in."

Watt said he was shifting funds to the Bureau of Mines in his department to emphasize "production-oriented research" and would check departmental policy to make sure it allows mineral companies access to all federally owned lands. Such changes were needed, he said, because "we are importing from foreign nations the most critical element of our civilization . . . strategically important minerals."

The nation now imports all its uses in manganese, which goes into steel, and in cobalt, which hardens steel, Watt said. Concern for U.S. access to manganese nodules on the ocean floor was one reason he "communicated with Secretary [Alexander] Haig" of the State Department to suspend the Law of the Sea treaty talks, he said.

Watt reported that of 62 minerals now being stockpiled, only 21 have been collected in amounts large enough to be useful during a halt in foreign supply, Cobalt is only at 48 percent of estimated needs, he said, and some of it "is unsuitable for high technology jet steel." He did not elaborate.

Another $12 billion would be needed to buy enough minerals to fill the stockpile, a Watt aide said; filling it from domestic sources would cost half as much.

Most members of the subcommittee applauded Watt's efforts, particularly Rep. Jim Santini (D-Nev.), who is sponsoring legislation to provide tax incentives ans a White House coordinating body to spur mineral development. "We are in an area of resource war," and have lost the chromium round and the oil round, he said. "We cannot afford to lose round three, because we're not in a 10-rounder," he said.

Asked about the environmental impact of increased mining and smelting, Watt said the law provides for "proper environmental safeguards. There is no basis for emotional blowout on this issue. We will bring back the smelting industry in a way that will be sound for America in every sense."