Bombs exploded at the Swiss and Russian embassies in Athens on Tuesday and police found suspect packages at two other embassies in a wave of parcel bomb attacks in the Greek capital.
Police linked the attacks to Greek leftist guerrillas. Small bomb and gas canister attacks have been frequent in Greece since 2008 when the police killing of a teenager sparked the country's worst riots in decades.
"A package was handed in at the entrance of the Swiss embassy in Athens today. Checks by our local employees revealed traces of metal," said Swiss Foreign Ministry spokesman Georg Farago. "When the external packaging was removed, the contents burst into flames," he said, adding that there were no injuries.
Tuesday's parcel bombs included one outside parliament, addressed to the Chilean embassy. Bombs were also found at the Chilean and Bulgarian embassies and one was intercepted at the offices of a courier company addressed to the German embassy.
"It seems that this is a continuation of yesterday's attacks and that Greek guerrillas are behind it, but we are still investigating," police spokesman Thanassis Kokkalakis told Reuters.
Chilean ambassador Carmen Ibanez said the package detonated by Greek police was an explosive device and it was addressed to her.
"It was addressed to the ambassador, in this case me," she told Chile's Radio Cooperativa.
A second suspect package addressed to the Chilean embassy was found to contain no explosives.
"Such deplorable actions terrorize neither the members of parliament nor parliament (itself)," the semi-official Athens News Agency quoted parliament speaker Filippos Petsalnikos as saying in parliament. "Such actions are unacceptable, contemptible and condemnable."
Greek political analysts say the attacks are largely symbolic and may have a variety of motives, such as showing urban guerrillas' opposition to capitalism and to a European Union/International Monetary Fund austerity plan Greece signed in return for aid which saved it from bankruptcy.
After the arrests of more than a dozen suspected members of guerrilla groups this year, the attackers may want to demonstrate they are still active. Foreign targets attract more media attention than attacks on Greek institutions.
On Monday, a parcel bomb detonated at a courier office in Athens, slightly wounding an employee. Greek police then arrested two suspects carrying two more bombs, addressed to French President Nicolas Sarkozy and the Belgian embassy.
Police on Monday intercepted a third bomb found at another delivery company and destined for the Dutch embassy.
Police officials said the quantity of explosive material in the devices that went off or were detonated on Monday and Tuesday was, in most cases, too small to kill anyone.
"The prime suspects would have to be the anarchists or far left as usual. If this is it, the story will fade but if there's another flurry tomorrow it's a different matter," said Control Risks Western Europe analyst, David Lea.
Blanka Kolenikova, an analyst at IHS Global Insight, said such attacks might proliferate at a time of austerity in Greece. "...Given that left-wing militants tend to blame the country's fiscal woes on "wheels of capitalism," the unpopular cost-cutting measures could see recruits to such groups increasing," she said.