President Reagan designated Monday "Helsinki Human Rights Day" to mark the 13th anniversary of an East-West accord he belittled and opposed as a presidential candidate.

In a written proclamation, Reagan said the 35-nation Helsinki Final Act, which committed the signatories to ensuring certain basic rights, "spawned a dynamic process" that stands as "one of the most important developments in East-West relations in the post-World War II period."That stood in contrast to the criticism Reagan leveled at President Ford for signing the agreement in 1975. At that time, he charged the United States should not sign an agreement the Soviets could not be trusted to obey.

Reagan noted Monday that a lack of full compliance by the Eastern Bloc still leaves provisions of the Helsinki accords unfulfilled.

Reagan said: "On this occasion we call upon all signatories of the Final Act to honor in full its solemn principles. Let us pledge to spare no effort in striving toward this goal."