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Marta Kaczynska, daughter of the late Polish president Lech Kaczynski, and Jaroslaw Kaczynski, his twin brother, walk during the funeral at the President's Palace in Warsaw on April 17. ((Ints Kalnins/Reuters))

Polish opposition party leader Jaroslaw Kaczynski says he will run in early presidential elections called after his twin brother was killed in a plane crash.

The elections were called for June 20, after President Lech Kaczynski, his wife Maria and 94 others were killed April 10 in Smolensk, in western Russia.

They were travelling to Russia to attend a memorial for thousands of Polish army officers executed in the Katyn forest in 1940 by the Soviet NKVD secret police.

"The good of Poland is a common duty that requires an ability to overcome personal suffering, to undertake the task despite a personal tragedy," Jaroslaw Kaczynski said.

The president's term was to expire in December. His brother said Monday he will run to continue the late president's mission.

The twin politicians first won fame as child actors in the 1962 hit film The Two Who Stole The Moon.

They became politically active when they joined the anti-communist opposition in the 1970s. They later served as advisers to the Solidarity movement in the 1980s and served briefly as advisers to Solidarity leader Lech Walesa during his 1990-95 presidency.

The twins founded the Law and Justice Party in 2001. In 2006, Lech Kaczynski appointed his twin brother as prime minister, a post he filled until he was defeated in a 2007 general election.

Parliamentary Speaker Bronislaw Komorowski, who automatically became president upon the death of Kaczynski, is currently the front-runner in the election race. He is a member of the governing Civic Platform party.

Also in the running is Grzegorz Napieralski of the Democratic Left Alliance. Napieralski is running in place of Jerzy Szmajdzinski, who died in the same plane crash that claimed Kaczynski.

If no one candidate can garner more then 50 per cent of the vote, a run-off will be held July 4.

With files from CBC News