WARSAW, Poland -- A Polish university researcher driven by nationalistic and anti-Semitic hatred was arrested for planning to detonate a four-ton bomb in front of the Parliament building in Warsaw with the president, prime minister, government ministers and lawmakers inside, authorities said Tuesday.

Prime Minister Donald Tusk said the suspect and his plot were discovered as investigators looked into Polish links to the Norwegian mass murderer Anders Behring Breivik. Polish security officials have said that Breivik bought small amounts of material for his bomb-making in Poland.

The foiled attack comes as the far-right movement appears to be growing in Poland, and as tensions simmer between Tusk's centre-right government and its main rival, the conservative Law and Justice party led by Jaroslaw Kaczynski.

Kaczynski recently accused Tusk and other leaders of "murder" in the 2010 plane crash that killed his brother, the late President Lech Kaczynski, and 95 others. A state investigation found the tragedy was an accident caused by bad weather and human error, but Kaczynski has been calling it an assassination.

Tusk said the dramatic plan to assassinate Poland's leaders shows that it is "high time to abandon a language of violence and hatred in public debate."

Prosecutors said Tuesday that they arrested the suspect in Krakow on Nov. 9. They said he is 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 the suspect was motivated by nationalistic, xenophobic and anti-Semitic ideas, but that he does not formally belong to any political group. He has refused psychiatric testing, they added.

The man, who was not identified by name, was building bombs himself and also had detonators, said prosecutor Mariusz Krason. The suspect planned to launch his attack outside Parliament when the leaders and legislators were there, but hadn't set a specific date, said Krason.

"He believed that the current social and political situation in our country is moving in the wrong direction" and that those in positions of power are "foreign," Krason said. "In his opinion they are not true Poles."

The prosecutor did not explain further, but extreme anti-Semitic thinking holds that Jews are not true Poles and that they secretly control power in Poland. In truth, Poland's Jewish community is tiny -- several thousand in a country of 38 million -- and very few Jews hold political positions in the country.

The rector at the suspect's university, Wlodzimierz Sady, said the man was a chemist who taught courses and carried out research. He did not raise any suspicion until his arrest, Sady told The Associated Press. "This is serious; we are all in shock," Sady said.

Authorities said the man intended to put four tons of explosives in a car and detonate them outside the Parliament building in the heart of the capital while President Bronislaw Komorowski, Prime Minister Donald Tusk and Cabinet ministers were inside, along with the members of the 460-seat lower chamber.

"The threat of an attack was real," said Artur Wrona, a prosecutor who was among several officials who gave the details of the thwarted terror attack at a news conference in Warsaw.

Krason said the man has confessed in part to the suspicions against him, including planning an assassination of the state leaders. If he is convicted he could face up to five years in prison.

Two others working with him were also arrested for the illegal possession of weapons and two more have been questioned.

The investigation and arrests are being led by the Internal Security Agency. The group published film footage of test explosions in a rural area made by the suspect and found among his possessions.

Both the president and the prime minister were informed of the assassination plan and the investigation before the news was released to the public, said Joanna Trzaska-Wieczorek, a spokeswoman for the president.