Athens, Greece (CNN) -- Police cordoned off one of the busiest thoroughfares in the heart of the Greek capital Thursday as a bomb disposal team investigated a suspicious package found at the entrance to a bank.
"This is the second bomb I've been to today," said one motorcycle police officer, who said he was not authorized to release his name to journalists, as he guarded a police line blocking off the five-lane Vassilissis Sophias Avenue, less than a block away from the Greek parliament building.
Moments later, a bomb disposal expert dressed in the heavy green armor made famous in the movie "Hurt Locker" walked briskly away from the suspicious package. Another member of the team counted down loudly in Greek, and then a controlled explosion echoed down the empty boulevard.
Authorities later said the package was not a bomb, but that wasn't the case earlier Thursday, when police destroyed another parcel at a courier office. Hellenic Police spokesman Maj. Athanasios Kokkalakis confirmed the parcel contained a "booby trap bomb."
The parcel was addressed to the French Embassy in Athens and the bombers put the archbishop of Athens as the sender of the package.
Greek officials said it was the 14th explosive device to be discovered originating from Greece in the past four days.
The events came as the two suspects in the largest letter-bomb campaign in Greek history were remanded into custody after appearing for testimony before a prosecutor, the Citizens Protection Ministry said.
The two men are accused of participating in a wave of attempted bombings that has forced the Greek government to suspend air postal deliveries outside of the country for 48 hours. They were arrested in Athens on Monday in possession of two parcel bombs, Glock pistols, a bulletproof vest, and a wig.
Many of the packages were addressed to various embassies in Athens, but one arrived at German Chancellor Angela Merkel's office in Berlin and another, addressed to Italian Prime Minister Silvio Berlusconi, made it to Italy.
Panagiotis Argyrou, 22, and Gerasimos Tsakalos, 24 were also in possession of a delivery slip for another parcel containing an explosive device which had been delivered to a courier service and was addressed to the Embassy of the Netherlands in Greece, police said.
"These are stake-holders ... important members of a terrorist group," Kokkalakis said.
Greek authorities have stressed that they believe the wave letter bombs is the work of a home-grown Greek terror group that does not have ties to international organizations like al Qaeda.
Before this week's attacks, one of the suspects, Argyrou, already faced an arrest warrant for his alleged membership in an illegal organization called the Conspiracy of Cells of Fire.
Both suspects have so far refused to cooperate with authorities, Greek officials said.
"Until this moment, they keep silent. They don't talk to anyone," Kokkalakis told CNN. "It is their strategic tactic."
When they appeared Thursday before a prosecutor Athens, they refused to testify, saying they "do not want to take part in this process." They were then remanded into custody.
For decades, leftist- and anarchist-inspired radical groups have carried out acts of political violence in Greece.
The most notorious and deadly of these groups, November 17, claimed responsibility for the assassination of the British Embassy Defense Attache Stephen Saunders in Athens in 2000.
Greek police, backed by British investigators, eventually succeeded in arresting the masterminds of November 17 in the years that followed.
Terrorism experts say they have seen an increase in Greek acts of terror since the 2008 shooting death of a Greek teenager by police in Athens. That incident sparked angry riots and a wave of small bomb attacks on banks and Greek police. The group Conspiracy of Cells of Fire is believed to have emerged during this period.
"This new generation of terrorists have a different motive ... money, publicity," said Ioannis Michaletos of the Institute for Security and Defense Analysis in Athens. Michaletos compared these groups to the anarchists who terrorized Europe at the start of the 20th century.
"They don't have a specific leftist ideology," he said. "They just state in their proclamations that their aim is to destroy the system."
In June 2010, a Greek police officer was killed opening a letter bomb that was addressed to the country's top law enforcement minister. Authorities have so far avoided linking that deadly attack to this week's parcel bombs, which apparently contain smaller amounts of explosives and have so far wounded one female employee of a private courier service.
In fact, some Greek officials have sought to downplay the threat posed by this week's letter bombers, by describing the suspects as young, poorly trained amateurs.
"The police found them with bus tickets and cards to make telephone calls. A professional wouldn't do this," said Vassilis Papadimitriou, a spokesman for the office of the Greek Prime Minister.
But the letter bombers have succeeded in forcing the Greek government to take the unprecedented step of halting international parcel delivery for 48 hours. They also have further rattled a society that is already struggling to deal with a deep financial crisis.
Greek Prime Minister George Papandreou denounced the bombers Wednesday, accusing them of trying to destabilize his government's efforts to rescue the Greek economy.
"Democracy will not be terrorized," Papandreou announced on local television.