Patriarch Kirill I of the Russian Orthodox Church spoke at a service on July 15 to consecrate a church near a forest where thousands of Polish army officers and intelligentsia were massacred by Stalin’s secret police in 1940.

Kirill also remembered the thousands of Russians who were slaughtered there, many for their religious faith, and said the site should serve as a place to unite Russians and Poles.

The Katyn Massacre ― in which about 22,000 people were killed ― is named after the forest in the Smolensk region near the Polish border where it took place.

Many of the Poles killed in 1940 were Orthodox Christians, of which the country has a large minority.

For decades, the Soviet Union covered up all traces of the massacre, which decimated the Polish military, claiming it had been carried out by the Nazis. In the post-Soviet era, Russia for years angered Poland by refusing to acknowledge the full scale of the killings or recognize them as a crime. The event continues to affect Polish-Russian relations.

The area experienced another tragedy in 2010, when a plane carrying Polish president Lech Kaczynski and 95 others to a memorial ceremony at the site crashed. Catholic Bishop Tadeusz Plozki and Orthodox Bishop Miron Chodakowski were among clergy who died.

At the service, Kirill praised Protopresbyter Semyon Fedoronko, who was an Orthodox chaplain in the Polish military and died at Katyn. Federonko’s granddaughters attended the service.

“He was sent to Moscow and questioned there, and was offered the opportunity, since he was Orthodox, to betray his spiritual children,” said Kirill. “He could easily have agreed and remained alive. But he said that he is a priest and a Christian and must return to his spiritual children, and he was shot to death here together with the Polish officers.”

Kirill said the memorial site should unite Russian and Poles.

“I am certain that the time has come to recognize that Katyn is a horrific symbol of our common tragedy, and in understanding this, to reach out to each other as brothers and sisters who have endured the sorrow and tragedy of Katyn,” he said.