Walk into any bookshop or department store in Warsaw and you’ll spot rows of the sombre-sleeved DVD for sale. Andrzej Wajda’s Katyn is a national phenomenon; since it opened across Poland in September it has been seen by 2.9 million people. Everyone in Poland knew about the Katyn Forest massacre, but for the 45 years of Soviet rule no one was allowed to deviate from the official line: the Nazis had done it.

In March 1940 Stalin ordered the killing of some 22,000 Polish officers, including many lawyers, doctors and professors. President Gorbachev finally acknowledged his country’s responsibility for the crime in 1990, and two years later President Yeltsin gave Lech Walesa, Poland’s new leader, Stalin’s original order to kill the officers. The slaughter of the country’s elite at Katyn and other sites contributed to Stalin’s intended destruction of the Polish intelligentsia.

Wajda’s film Katyn will have its British premiere at the BFI Southbank on April 22, followed in May by a season of the director’s films.

Wajda was only 13 when his cavalry officer father was killed, having first been held in Kharkov prison in the Ukraine. His remains were never formally identified and Wajda’s mother spent the rest of her days hoping against hope that he would return. “I can’t really talk about him,” says the 82-year-old director, looking uncomfortable, “except to say that he was my ideal and that he died at the age when I needed him the most.”

Throughout his career, Wajda – who started out as a painter – has made films that explore the complex history of his homeland. He started in 1954 with Generation, the first in a Second World War trilogy that included Kanal and Ashes and Diamonds. Most memorable are The Promised Land, about early capitalism in Lodz, Man of Marble, about the fall from grace of a Stakhanovite worker, and Man of Iron, set during the birth of Solidarity in Gdansk.

Although Katyn was a contender for this year’s foreign-language Oscar, Wajda says he made it for Polish audiences. “I wasn’t even sure young Poles would be interested,” he says. In the end, most Poles wanted to know about this sombre chapter in their past.

Katyn is a film that Wajda never thought he would make because he had not expected the Soviet Union to collapse (“I thought it would last for ever”). But when he decided he would, it wasn’t money he needed but a script. It took him ten years to produce the screenplay, using stories from the diaries kept by ordinary Poles between 1939 and 1945. In 2007 Andrzej Mularczyk wrote the novel Post Mortem and Wajda was attracted by some of its characters, so he used that too. “Until then I had been overconcerned with the story’s political and historical structure.”

Rather than the officers’ viewpoint, Katyn follows the wives, mothers and sisters who waited for their loved ones. In the film’s last, gruelling scene, we witness the systematic slaughter of the officers, a single bullet crossing the skulls of the handcuffed men, the mass graves then covered with earth. “It was an exceptional situation,” Wajda says, “the greatest of treasons. Although they had been taken prisoner by the Russians, the officers trusted them. They were convinced that they would fight against the Germans.”

As to the wisdom of reopening old wounds, Wajda is unequivocal. “We are shaped by our history,” he says. “Some wounds heal only when we become aware of them, and that is the role and the duty of art.”

Katyn was surprisingly well received in Russia, where critics saw it as an attack on Stalin and not on the Russian people. Wajda was pleased to learn the day we met that the opposition Russian journal Novaya Gazeta had just said that Polish prosecutors should be given access to the total 183 volumes of Katyn documents, and not just the 67 they had seen so far. “It would be my life’s greatest achievement if my film could contribute to their being released,” he says.

“In the 18th century, we were erased from the map for 100 years. We survived thanks to our two fatherlands: the earth we lived on and our language and literature.” He says he would love to make a film about contemporary Poland. “The problem is that it is very difficult to grasp and turn into images. Where are today’s heroes?”

The British premiere of Katyn will be at the BFI Southbank (020-7928 3232) on Tuesday, followed by a Wajda season, May 2-31, as part of the sixth Polish Film Festival (kinoteka.org.uk)

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