A coalition of environmental groups is preparing to sue the Department of Interior over the federal strip mine control regulations it is expected to issue in final form this week.

The groups will contend that Interior's regulations, affecting slightly more than half of the nation's coal production, are significantly weaker than Congress intended when it passed a strip-mine law in 1977.

Once the regulations are issued, the states will have until June 1980 to start reclamation programs based on the federal standards or see Interior take over enforcement.

Controversy swelled last month when Interior disclosed that it was meeting with President Carter's Council of Economic Advisers -- two months after the public comment period ended -- to discuss possible inflationary aspects of the new regulations.

A suit challenging the legality of the CEA intervention, filed by the National Wildlife Federation, the Natural Resources Defense Council and the Council of Southern Mountains, was dismissed by a federal judge here.

Although Interior could make changes in its proposals before they become final -- probably on Thursday -- the gist of the regulations became known when the department published its environmental impact statement several weeks ago.

Thomas Galloway, an attorney for the same coalition of environmentalists, said legal challenges probably will be aimed at these key areas:

Regulations proposed last year that have been altered to remove an individual citizen's right of access to a strip mine site with a state inspector, as well as his right to sue state enforcers.

A feature called the "state window" -- allowing a state to depart from the general requirements as long as it meets the minimum standards. Interior adopted that approach to ease a state's application process, but Galloway said it creates the possibility of a "gaping loophole" in enforcement.

Interior's apparent acceptance of four of five major CEA complaints about the regulations, resulting in less stringent provisions on air pollution, stream sedimentation, mining waste disposal and permit issuance.

"We consider all of these points grounds for litigation," Galloway said. "These things will allow weak programs to be set up across the country and they really go to the heart of what Congress intended with the law."

"The state window procedure and the exclusion of citizens from monitoring state enforcement programs have nothing to do with inflation -- if that is what they argue," he added. "They represent a slap in the face, an abandonment of the program and a reversal of congressional intent."