The Civil Aeronautics Board yesterday granted two charter and two scheduled airlines temporary authority to fly between several U.S. cities and Belgium and The Netherlands.

In granting the awards, the board said it hoped to demonstrate to European nations that airline competition can work in international markets as well as in this country. The United States will be negotiating air agreements with many of these nations in the next year.

"The most effective way of persuading these governments is to provide a living demonstration to the citizens of those countries of the benefits (promised by) accentuated competition," the board said.

The authority went to:

Capitol International Airways, between Brussels and Chicago, New York and Boston.

World Airways, between Amsterdam and Baltimore-Washington, Chicago, Detroit, Oakland and Newark.

National Airlines, between Amsterdam and New York.

Northwest Airlines, between Amsterdam and New York and Chicago.

The authority is effective Sept. 12, and all flights will be scheduled.

The board said the temporary authority will be for one year, or until 60 days after a final decision on a low-fare air treaty between the United States and the Benelux nations (Belgium, The Netherlands and Luxembourg). That decision is targeted for June 1979.

The board said the awards will provide experience for U.S. carriers in advance of a treaty agreement, maintain competitive balance between the scheduled and charter carriers and demonstrate to other European governments that competition can work in the international market.

"We are faced right now with the need to bargain for liberalized air relations with a number of European states," the board said. "We must persuade them that protectionism and cartelization are anachronisms (if they ever had validity) and are an inefficient way of achieving their national aviation objectives."