Polish authorities have arrested a radical nationalist who planned to blow up parliament and had links to the right-wing extremist who murdered dozens of people in Norway last year.
The suspected plot – to detonate a bomb outside parliament when the country's most senior officials were inside – was the first of its kind since Poland threw off Communist rule more than 20 years ago.
It is likely to bring renewed scrutiny on radical right-wing groups inside Poland, which are fiercely opposed to the liberal government, and on the way extremists intent on violence share information with each other across Europe.
"This is a new and dramatic experience," said Prime Minister Donald Tusk, who, according to prosecutors, was one of the intended targets of the assassination plot, along with the President. "This should be a warning."
Prosecutors on Tuesday said the suspect, a 45-year-old scientist who works for a university in the southern city of Krakow, planned to plant four tonnes of explosives in a vehicle outside parliament and detonate it remotely.
The plot had parallels with Anders Behring Breivik, the Norwegian who set off a bomb in Oslo last year and then went on a gun rampage on a nearby island, killing a total of 77 people.
"The would-be bomber did not hide his fascination with Breivik. This should not be ignored," Mr. Tusk told a news conference.
The Prime Minister said that investigators had found practical connections to Mr. Breivik too: The Norwegian bought bomb components in Poland, he said, and an analysis of his contacts helped lead Polish intelligence to the suspect.
Briefing reporters in the Polish capital, prosecutors said the suspect had assembled a small arsenal of explosive material, guns and remote-controlled detonators and was trying to recruit others to help him.
A video recording taken from the suspect, who has not been publicly identified, showed what prosecutors said was a test explosion he conducted, sending up a huge cloud of dust and leaving a large crater in the ground.
"He claims that he was acting on nationalistic, anti-Semitic and xenophobic motives," prosecutor Mariusz Krason said.
"He believed the situation in the country is going in the wrong direction, described the people ruling Poland as foreign and said they were not true Poles."
can trim from here if needed//Poland is one of several European countries where far-right groups have become more visible in the past few years, a trend some scholars say is partly linked to hardship caused by the financial crisis.
In Hungary, opinion polls show strong support for the far-right Jobbik opposition party. Greece's ultra-nationalist Gold Dawn is backed by 10 per cent of the population.
Most right-wing groups renounce violence, but some on the margins are more radical.
Roger Eatwell, a professor at Britain's Bath University who studies the far right, said though extremists intent on violence did not operate in networks, they do share information across Europe's borders.
"They look at each other through the Internet, they sometimes correspond with each other through the Internet, though they have to be careful because that is monitored," he said. "The bad news is that they are very hard to police."