Ukrainian authorities have reburied near the capital, Kiev, the bodies of some 2,000 people killed by the Soviet secret police more than 60 years ago.
The existence of mass graves was denied under Communist rule.
Relatives of the victims watched as red coffins were lowered into graves and blessed by a priest at the ceremony.
The bodies, including 474 Poles, were dug up this year in Bykovnya, where tens of thousands are thought to have been dumped during the 1930s and 1940s.
Under Communist rule, the existence of the mass graves in Ukraine was denied.
It was only in the 1990s, after the fall of the Soviet Union, that the mass graves were acknowledged and memorials built.
About 100 people including relatives of the victims attended the sombre ceremony in a forest outside of Kiev on Saturday.
One of those attending, Maria Marzhetska, said her father had been seized in 1937. She only discovered his fate 60 years later.
"I was eight years old. There were just three of us - father, mother and me - and they took him," Ms Marzhetska told the Reuters news agency.
"Every morning, every evening we were at the police station," she said.
Andrzej Przewoznik, the general secretary of Poland's Council for the Protection of Monuments to Struggle and Martyrdom, said the site was a very important place for Poles.
"This is a place where we would like the Polish [Catholic] cross and Polish memories of those people resting in the Bykovnya forest to be," he said.
Those buried on Saturday were tortured and later killed by the much-feared Soviet secret police, the People's Commissariat for Internal Affairs or NKVD.
According to various estimates, more than 100,000 people were killed by the NKVD between 1936 and 1941 during Joseph Stalin's rule.