On December 13, 1981, communist-era strongman Gen. Wojciech Jaruzelski imposed martial law to stifle rising opposition, headed by the Solidarity movement.
It was the start of a dark chapter in modern Polish history that saw thousands of opposition activists jailed and dozens killed.
In a ceremony at a Warsaw museum in the morning, officials were expected to pay tribute to communist-era political prisoners and post-World War II resistance fighters who suffered brutal repression at the hands of Poland's former communist authorities.
A religious service was also due to be held at the site to honour the victims of the communist-era crackdown.
In the evening, President Andrzej Duda was scheduled to attend the annual "Light of Freedom" tribute at Piłsudski Square in central Warsaw.
Officials have encouraged people to light candles in the windows of their homes in a symbolic gesture to commemorate the victims of communist oppression.
According to a parliamentary report compiled in the early 1990s, more than 90 people were killed during martial law, which lasted formally until July 22, 1983.
On the night of December 13, 1981, more than 6,500 opposition activists were arrested and interned.
During martial law Poland’s communist regime suspended political and workers’ organisations and introduced a curfew.
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Source: IAR, PAP