UNC Resoruces Inc., a uranium-and coal-mining concern based in Falls Church, confirmed yesterday that it has made an unsolicited proposal to merge with Western Airlines, the Los Angeles-based airline whose proposed merger with Continental Airlines currently is pending at the Civil Aironautics Board.

Although UNC officials declined comment on the specifics of their proposal, Western said that UNC offered to provide Western share holders with a combination of cash and UNC securities that would yield them about a 50 percent premium above the last several months' average market price of the Western stock. Western's common stock has ranged between $6 and $11.63 during the year.

Dominic P. Renda, Western's president and chief executive officer, said Western's investment bankers -- Salomon Brothers -- and lawyers have been asked to evaluate UNC's offer, and their views, will be presented to the board of directors.

Western's disclosure statement about the UNC offer said UNC recognizes that its proposal is inconsistent with the pending Western-Continental merger agreement. According to Ray Silvius, Western's vice president for corporate affairs, Western has a responsibility to its shareholders to assess the UNC proposal but for the moment at least will be proceeding with its merger agreement with Continental.

Continental said yesterday it has a valid merger agreement with Western approved by the boards of both companies and "expects Western to live up to that agreement."

Western's disclosure of UNC's proposal came late Tuesday following receipt of a letter from Keith A. Cunningham, UNC's president and chief executive officer, outlining the proposal. Cunningham had paid Renda a visit the previous Thursday and indicated interest but had made no proposals, Western officials said yesterday.

Cunningham, reached yesterday, declined to respond to any questions about why the uranium and coal company might want to merge with an airline, whether it had bought any stock in Western or the specific proposal it made. He would say only that the company might have more to say early next week.

Western and Continental announced in August that they would try again to get CAB approval to merge; the board had turned down their previously proposed merger in July 1979 on grounds that a merger between two airlines serving so many of the same cities would have lessened competition.