ATHENS — A wave of parcel-bomb attacks culminating in last month's explosion inside Lucas Papademos' armored Mercedes — which put the former prime minister, his driver and bodyguard in hospital — has exposed what might be Greek premier Alexis Tsipras' weakest flank: law and order.

While small-scale attacks on businesses, police and politicians by extreme left-wing groups are nothing new in Greece, the increasingly ambitious choice of target has experts and politicians concerned. In March, a parcel bomb from Greece was intercepted on its way to German Finance Minister Wolfgang Schäuble; another wounded an employee of the International Monetary Fund in Paris.

Opposition leader Kyriakos Mitsotakis of New Democracy blames Tsipras' left-wing party, Syriza, for fomenting the anti-establishment hatred that he says is behind the attacks. He accuses the prime minister of failing to take adequate action to protect potential targets, including himself, if — as he confidently expects — he becomes the next Greek prime minister. The next general elections are scheduled for 2019.

"It’s very, very worrisome — it’s worrisome for me in terms of my personal safety, and it’s worrisome in general," Mitsotakis told POLITICO during a visit to Brussels. "It is an issue I deeply care about because I lost a member of my family back in 1989 to domestic terrorism.” The scion of a political dynasty and son a prime minister, his brother-in-law was shot dead in 1989 by the far-left terrorist group November 17.

Mitsotakis visited Papademos in hospital and said the 69-year-old former central bank chief was "lucky to be alive." Tsipras himself tweeted after the attack: “I condemn unequivocally the attack against Lucas Papademos. I wish a speedy recovery to him and the people who accompanied him.”

The self-styled "urban guerrilla" group Conspiracy of the Cells of Fire (SPF), which had been believed to be defunct since a wave of arrests in 2011, has claimed responsibility for some of the bombs. Security experts say its leaders continue to recruit new members and direct attacks from behind bars.

“We are the only country [in Europe] that has domestic terrorism of the extreme left," said Mitsotakis, blaming Syriza for fomenting a "real culture of hate" when it was in opposition, and of doing little about the violence since it has been in power. "I haven’t seen anything that convinces me that they have a real willingness or desire to address this issue,” he said.

The ruling party, in turn, accuses New Democracy of "vulgar political exploitation" of the situation, saying this too is "a danger to democracy."

Greece has "some of the toughest law provisions for terrorist activity" and is "making progress in confronting members of terrorist groups," argued Syriza MP Nikos Paraskevopoulos.

Others disagree — and even warn that radicalized Greek youth could soon resort to even more lethal forms of violent protest.

‘Lost control’

While Greece's "urban guerrillas" claim they want to instigate a revolution, experts say its members are typically well-educated youngsters from middle-class families motivated by a desire to verbalize their hostility to the system. Claims of responsibility for attacks are often accompanied by lengthy theoretical arguments and diatribes against politicians.

“They are not poor kids," said Mary Bosi, a professor at the University of Piraeus and an expert on Greek left-wing terrorist groups. "They want to show their dissatisfaction with the state and its institutions."

In a country where youth unemployment hovers around 45 percent, frustration at the lack of opportunity runs high. "We see that all the time in Greece, of course — they are angry, they are jobless. They study and they have no future, this is part of a big problem,” said Bosi.

The SPF typically uses small quantities of explosives — just enough to wound but also escape detection by postal sorting-office screening machines — and targets prominent economic and political figures seen as being somehow responsible for Greece's financial troubles.

An economist and former Bank of Greece governor, Papademos acted as caretaker prime minister until May 2012 after the resignation of George Papandreou during one of the country's most turbulent periods.

The group's preference for weak explosives suggests it is more concerned with sending a message than killing anyone or overthrowing the system, said Bosi. But as Greece continues to sink under the weight of its debt burden, its members could very well resort to more drastic measures. “My feeling is that we will see new organizations appearing. I don’t want to see more lethal organizations but I am afraid this situation is a breeding ground for people who will be more active or more lethal,” she said.

“The violence has been almost exclusively from the left in recent years” — Kyriakos Mitsotakis, opposition leader

The central Athens neighborhood of Exarcheia, a regular battleground between molotov-throwing youths and riot police, is singled out as the breeding ground for such groups. It has been a virtual no-go zone for police since a 15-year-old boy was killed by a policeman there in 2008, which led to nationwide riots.

“It’s an area where the state has completely lost control,” said Mitsotakis.

Minister of Citizens Protection Nikos Toskas, who didn’t respond to requests for comment for this article, has pledged to normalize the situation in the neighborhood and drive out criminal groups.

A history of violence

Greece's economic crisis and Syriza's rise to power has tended to focus media attention on the far-right group Golden Dawn, which grew to become the third-biggest party in the Greek parliament and won 7 percent of the vote in September 2015 elections. About 69 of its members and all of its parliamentary group are currently on trial for a host of charges, including directing a criminal organization.

However, Mitsotakis played down the impact of Golden Dawn on Greek society, saying it was "so extreme and so vulgar" that it was marginalized. “It’s as if they don’t exist,” he said. “The violence has been almost exclusively from the left in recent years.”

Like many European nations, Greece was shaken by left-wing terrorism in the 1970s and 1980s. Marxist-Leninist groups such as November 17 (17N) and Revolutionary People’s Struggle (ELA) carried out high-profile bombings and assassinations, including the murder of CIA station chief Richard Welch in 1975 and of Stephen Saunders, a military attaché at the British Embassy, as recently as June 2000.

While those groups were eventually dismantled, the latest crop of Greek radicals poses a new set of challenges, according to Bosi. Where older terror organizations had "an ideological" understanding of their purpose and a clear political agenda, newer groups are self-defined anarchists and nihilists, with no political agenda beyond making their anger public.

To Bosi, who was herself targeted by a bomb outside her home — no doubt as a result of her public stance against the guerrilla groups, she said — their "ideological vacuum" is particularly dangerous.

"Because when you have a school of thinking, you have limits to what you do," she said. "Now there are new targets, like you and me."

Stephen Brown contributed to this article.