The administration yesterday formally proposed an international aviation policy emphasizing - to no one's surprise - increased competition.

In other developments yesterday, Civil Aeronautics Board efforts to promote competition in domestic aviation as well continued to produce consumer benefits as two airlines proposed additional fare cuts.

If, as expected, President Carter adopts the proposed international aviation policy after a public hearing, it will be used as a guide for American negotiators in seeking new international air transport agreements with other nations. The proposed policy is consistent with general principles outlined for negotiators by the president last October and enunciated repeatedly by State, Transportation and CAB officials.

The policy sets six general objectives:

Creation of new and greater opportunities for innocative and competitive pricing.

Expansion of scheduled service by rules and removal of restrictions on charter operations.

Expansion of scheduled service by eliminating restrictions on passenger capacity, flight frequencies and airlines' route operating rights.

Elimination of discriminatory and unfair competitive practices faced by U.S. airlines abroad.

Flexibility to have more than one U.S. airline on international routes.

Permitting air service directly to other countries from more U.S. cities and improving the integration of domestic and international airline services.

Raymond Young III, deputy assistant secretary of Transportation for policy and international affairs, yesterday admitted the controversial Bermuda II Agreement signed last summer by the United States and the United Kingdom had a lot to do with the new policy undertaking.

American Airlines asked the CAB for permission to cut regular economy fares in half on 18 domestic routes beginning July 1. The half-price fare, to be called the "short stop," would be available on all of American's flights on the 18 routes without any restictions, such as advance purchase or minimun-stay or maximum-stay requirements. Passengers would make tagland segments of longer flights

The routes selected are the entry or tag-end segments of linger flights which are often unfilled, an American official explained. Area routes in which the fare would be offered are Baltimore-New York, Baltimore-Detroit, and Washington-Philadelphia.

Pan American World Airways asked the CAB for permission to institute an $89 stand-by fare between the West Coast and Honolulu beginning July 7. To take advantage of the fare, which is 40 percent off the normal coach fare, a traveler would have to buy a ticket before going to the airport, but there would be no other restrictions.