President Reagan suggested again yesterday that the Soviets' glasnost campaign of openness is a publicity stunt, and challenged them to make good on it by tearing down the Berlin Wall and establishing democracy in Eastern Europe.

In his weekly radio address from Camp David, Reagan marked next week's 26th anniversary of the Berlin Wall, repeating much of what he said in a speech at the 12-foot-high concrete barrier June 12 and reiterated two weeks ago in a speech here.

Referring to Soviet leader Mikhail Gorbachev's policy of increased openness, Reagan asked, "Does it mean genuine openness to speak, to write, to travel -- even to buy and sell, or is it more of a publicity show?

"As I said in Berlin in June, the way for the Soviets to demonstrate their dedication to true openness is to tear down the wall," he said. "That's not all they could do. At the end of World War II the Soviets promised free elections in Eastern Europe. Openness should mean fulfilling that promise.

"Openness should also mean freeing political prisoners, refuseniks and other prisoners of conscience. It should mean an end to Soviet imperialism, whether in Eastern Europe, Afghanistan, Angola, Cuba or Nicaragua."

The wall was built Aug. 13, 1961, by East German troops to prevent escapes. Since it went up, at least 74 people have been killed trying to scale it, the president said.