The Polish government today released nine members and sympathizers of the dissident Workers Defense Committee set up last September to aid workers imprisoned and dismissed after last summer's demonstrations against food price increases.

The releases came under a clause in a National Day amnesty that freed criminal offenders serving prison terms of up to one year and discontinued investigations in cases where the alleged offense called for a two-year term.

Inside Warsaw's Rakowiecka prison, where many dissidents were being released today, it was widely believed that the amnesty's main purpose was to free members of the Workers Defense Committee.

Also released today were five men still imprisoned after receiving sentences ranging from three to 10 years for offenses allegedly committed after last year's demonstrations. About 50 others have been released since last February when Polish leader Edward Gierek asked the Council of State to free them under a clemency act.

The Workers Defense Committee members released today were being held for investigation under charges arising out of their alleged involvement last May in demonstrations by students in the university town of Cracow. Those demonstrations of followed the death under mysterious circumstances of Stanislaw Pyjas, a student and activist in the Workers Defense Committee, which demanded a public inquiry into his death.

The release came after protests by Polish intellectuals and students, and more protests and expected in the atutumn from students returning from vacation. It seems certain that a trial of those arrested would have caused the authorities new embarrassment.

It is also known that the primate of Poland, Stefan Cardinal Wyszynski, had urged the Polish government to free the disidents. Many observers think his intervention may have been decisive.

Protests from abroad, like the letter signed by 140 U.S. writers and academics ranging from Edward Albee to Prof. C. Vann Woodward, are also believed to have influenced a decision that immediately improved Poland's human rights record before this autumn's Belgrade review conference on the Helsinki accords. Preliminary talks for the fall meeting are currently under way in Belgrade.