ATHENS, Greece — Greek investigators examining last week’s assassination attempt on a government minister are unraveling evidence of a network of urban guerrilla groups operating across Greece, Spain and Italy.

Europe’s international police agency, Europol, in its 2010 report noted a 43-percent increase over the past two years in what it terms “terrorist” strikes in these three countries.

In the latest attack in Greece, the minister for the protection of the citizen, Mihalis Chrysochoidis, was sitting just meters away from a bomb that blew up inside his offices last Thursday, killing his deputy.

Despite a drumroll of low-intensity terrorist attacks in recent years, this marked the gravest incident since the Greek Marxist guerrilla group 17 November was broken up by police ahead of the Athens 2004 Olympics. The granddaddy of Greek terrorist groups had been responsible for killing several Greek politicians, a CIA Athens station chief, a British military attache and a Greek former intelligence chief.

As much of western Europe concentrates its efforts on curbing Islamic extremism, analysts have identified common threads linking several of the groups operating across southern Europe, chiefly anarchism and anti-state sentiment.

A leading Italian anarchist theoretician, Alfredo Maria Bonanno, himself currently serving time in a Greek jail for bank robbery, points to an informal affinity among groups attracted to violence by specific social causes and with an ulterior motive of paralyzing the state.

Brady Kiesling, a former U.S. diplomat and author of “Diplomacy Lessons: Realism for an Unloved Superpower,” meantime identifies a clear link between Greek and Italian activists ready to resort to violence to achieve their aims.

“The personal friendships between Greek and Italian anarchists are clear at every level,” he said. “Greek police have seen so many people go back and forth from Italy — and Italian anarchists have historically been armed — that they’re right to look into this.”

Italian security forces defused three suspicious packages in March and April posted to the offices of the Italian prime minister and minister of interior as well as an older one targeting a military base outside Rome. A group calling itself the Informal Anarchist Federation claimed responsibility for those packages as well as package bombs sent to Greek targets in Spain, including to the embassy in Madrid and a Greek-owned bank. Greece's counterterrorism force announced that it was collaborating with Italian and French police.

However, Maria Alvanou, a lecturer in asymmetric threats at the Hellenic Military Academy, warned against attempts to draw a pattern of groups working in unison. “It seems there is a link but it’s too early to say if this is actual collaboration with abroad or just a copycat phenomenon,” she said.

“While the rest of Europe is busy dealing with jihadi terrorism, leftist terrorist networks are being resurrected in Greece,” Alvanou said. “They are coming back because Greece now has the kind of problems that Europe faced in the '70s: injustice, corruption weak infrastructure and democratic participation issues.”

The Greek-based anarchist group 325 often carries out Robin Hood-style supermarket raids and issues proclamations declaring that they want to “tear a hole in the guts of the European Union” through “an anarchism long based in the South European Mediterranean Triangle of Greece, Italy and Spain, [and] finding fertile ground to spread within many more minds not held by any borders and … receptive to the anarchist vision of a future world without Church, State and Capital.”

An alphabet soup of at least half a dozen groups make up Greece’s urban guerrilla scene, the most prominent being Revolutionary Struggle and the Conspiracy of Fire Nuclei. Secondary groups are Popular Revolutionary Action, the Guerrilla Terrorist Group, Popular Will and Ambush.

Urban guerrilla organizations prefer low-intensity bombs that usually explode outside commercial or political targets and are detonated in the early hours to avoid casualties. As the economic crisis impacted Greece last year, violence spiked with the killing of a counterterrorist policeman in a bombing claimed by a group called Revolutionary Sect.

Targets have included everything from the U.S. Embassy to the offices of security contractors, a television station, a forest authority facility, the house of an explosives specialist and local police stations. Last month, twin bombings targeted Athens’ Korydallos jail and a judiciary complex in the city of Thessaloniki.

“The whole anarchist movement in Greece is focused around solidarity with imprisoned comrades,” Kiesling said. “So it was clear that with enough people in jail there had to be some kind of retaliation against the police.”

Greek police arrested several suspected members of Revolutionary Struggle in March and claimed they had decapitated the group. Overnight, messages daubed on walls and distributed in the cafes of traditional anti-authoritarian neighborhoods disputed this and pledged revenge.

Last Thursday's bombing of Chrysochoidis’ office was seen as the promised retaliation. Half a kilo of professionally assembled explosives were secreted inside a metal box disguised as a vanity publication of the type regularly sent to Greek ministers, according to press reports. Once it reached the Ministry for the Protection of the Citizen, the A-3 sized package looked so harmless that it was left lying around the office for a full two days. Its humdrum appearance saved lives; by the time the minister’s deputy opened it at 8.30 p.m. last Thursday, most of the office’s employees had left.

Suspicions over last week’s ministry bombing is centering on a group calling itself Popular Will. The group, which dispatches its bombs through the mail, tried assassinating Chrysochoidis at his private office in February.

The name of Christos Karavelas — a businessman allegedly involved in a security scandal involving Virginia-based company Science Applications International Corporation, Germany’s Siemens and Greek politicians — was symbolically written on Thursday’s fatal package.

Popular Will may have appeared in a previous incarnation just before the Athens 2004 Olympics under the guise of a terrorist group calling itself Popular Rage. It may derive its name from Narodnaya Volya, the group set up by Lenin’s brother in Russia prior to the overthrow of the czar and which has the same meaning in Russian.

Anti-terrorist officials believe that a core of activists is responsible for terrorist attacks in Greece but use multiple organizational names to cover their operational tracks.

Despite an emotional funeral and wall-to-wall coverage by Greece’s media, there have been few public displays of anger about the June 24 attack. Greek society’s attitudes to terrorist strikes are ambivalent and range from nonchalance to tacit support of urban guerrilla groups.

“Terrorism is basically a kind of public entertainment in Greece,” Kiesling said. “It doesn’t have anything to do with ordinary people at this point, so it’s become an empty spectacle, like watching Greek Idol.”