A university researcher has been arrested over an alleged plot to detonate a four-tonne bomb in front of the parliament building in Warsaw when the President, Prime Minister, government ministers and MPs were present.
Donald Tusk, the Prime Minister, said the suspect and his plot were discovered as investigators looked into Polish links to the Norwegian mass murderer Anders Behring Breivik.
Prosecutors said the suspect was a 45-year-old Polish researcher employed at the University of Agriculture in Krakow who had access to chemistry laboratories. He was in illegal possession of explosive materials, munitions and guns.
They said he was motivated by nationalistic, xenophobic and anti-Semitic ideas, but that he did not formally belong to any political group.