Updated

Polish authorities have arrested a man who was planning to detonate a four-ton car bomb in front of the Parliament building in Warsaw while the president, prime minister, government ministers and lawmakers were inside.

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

The suspect, who was not identified by name, was building bombs himself and also had detonators, said prosecutor Mariusz 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."

Krason did not explain further, but one strain of anti-Semitic thinking holds that Jews 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 did his own 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.