Twin brother of Polish president killed in air crash running to fill brother's vacant position

Jaroslaw Kaczynski, 60, became prime minister in 2006, heading a right-wing coalition that had tense relations with the European Union and Russia. He lost power in a general election in 2007.

Lech Kaczynski had been expected to run for re-election in October - although polls suggested he would lose.

While Jaroslaw Kaczynski could benefit from a significant sympathy vote in the wake of the tragedy, the Parliamentary Speaker Bronislaw Komorowski, who became  acting head of state after the crash, is expected to defeat Mr Kaczynski in the snap election on June 20.

The president, his wife and 94 senior officials were killed in a plane crash in Russia on 10 April.