KATOWICE, Poland (Reuters) -- Poland's President Lech Kaczynski has said he plans to attend a commemoration in April of the wartime massacre of 20,000 Polish officers by Soviet forces even though Moscow has not invited him.
On February 3, Russia's Prime Minister Vladimir Putin invited his Polish counterpart Donald Tusk to join him at the site of the 1940 massacre, the Katyn forest in western Russia, in a sign of improving relations between Warsaw and Moscow.
Russia has not invited Kaczynski. In protocol terms, President Dmitry Medvedev, not Putin, would normally invite a fellow head of state.
"I am glad Prime Minister [Tusk] is going there, but I am the highest representative of the Republic of Poland and I will be there as well. I hope I'll be given a visa," Kaczynski, a rival of Tusk, told reporters in Katowice, southern Poland.
The Katyn massacre is an emotive issue in Poland and Kaczynski, a right-winger who has often criticized Russia, has an eye on conservative voters ahead of a presidential election due this autumn in which he is expected to seek a second term.
Bilateral ties between Poland and Russia, strained over energy and security issues, hit rock bottom under Poland's previous conservative government which was led by Kaczynski's twin brother Jaroslaw.
Tusk has sought to improve relations with Russia, an important trade partner, since his centrist government took power in 2007, ousting Jaroslaw Kaczynski.
In a sign of better cooperation, a joint commission of Russian and Polish historians is due to publish a book later this year on the neighbors' difficult shared history. It is expected to include a common position on Katyn.
Russia admitted responsibility for the Katyn massacre only in 1990 but some of its archives containing historic documents related to the killings remain closed. Poland has demanded full access to the archives and the rehabilitation of the victims.
Relatives of the murdered officers, who accounted for a large part of Poland's prewar intelligentsia, want Russia to officially admit the Katyn massacre as a genocide.