Police forces from various European countries have joined together to hunt for Italian anarchists suspected of waging a letter bomb campaign against European targets. The bombs are believed to have all been sent from the northern Italian city of Bologna.
The letter bombs have so far caused no injuries. But they have revived memories in Europe of the days before the September 11, 2001, attacks in the United States, when political radicals were more feared than Islamic militants.
Authorities believe all the bombs have been sent from Bologna. The city's chief attorney Wednesday issued an order blocking the dispatching of all mail from Bologna that is addressed to European Union offices.
One parcel bomb was intercepted in The Hague on Tuesday at Eurojust, a European law enforcement group. Two mail bombs were foiled Monday, one addressed to the European Central Bank president in Frankfurt, Germany, and one to the director of the European police agency, Europol.
Security measures have now been tightened at European Union offices.
Last Saturday in Bologna, European Commission President Romano Prodi opened a package that burst into flames, but he escaped injury.
An Italian group calling itself the Informal Anarchist Federation had threatened a campaign against what it called the new European order just days before the first device was sent to Mr. Prodi.
The group also took responsibility for setting two other devices that exploded outside the European Commission president's house on December 21, causing a small fire.
Bologna's chief attorney has said he believes the letter bombs are the work of anarchists who are against any form of centralized power, in this case, against the European government.
A Bologna police spokesman said the same Italian anarchist group is believed to be responsible for all the attacks. He said Italian police were coordinating investigations with police forces in other European countries.