Greece's justice ministry on Wednesday sustained a cyber-attack, the second this month, after the arrest of a teenager accused of participating in the first hacking, police said.
"There has been another attack on the justice ministry website," a police press officer told AFP.
The attack was claimed in the name of hacker group Anonymous, which has carried out several high-profile international hits in recent weeks.
The hackers posted a message on the ministry site claiming an 18-year-old arrested by police on Monday was not related to the February 2 raid.
They also threatened to hit Greek tax offices next "to erase citizens' debt", according to parts of the message published in the press.
"We are Anonymous," said the message in Greek, posted under a 2008 picture of masked protesters in an Athens demonstration.
At the foreground of the picture is Loukanikos, a stray dog that has become an unofficial mascot for Athens protests and was cited last year in Time magazine's 'Person of the Year' award, which was dedicated to protesters in the Arab world, the crisis-hit EU, the United States and Russia.
"For each one arrested, three more will spring up," the message said.
In addition to the 18-year-old, who belongs to a Greek hackers' group, police were also seeking two boys aged 16 and 17 for the first attack on February 2, which criticised Greece's tough fiscal reforms and its decision to join a controversial anti-piracy deal.
"You have introduced a new dictatorship upon your people's shoulders and allowed the bankers and the monarchs of the EU to enslave them both economically and politically," said a statement in English read out by one masked hacker.
"Democracy was given birth in your country but you have now killed it," he added.
The hackers had also threatened to "deface" media and ministry sites unless Athens withdraws from the Anti-Counterfeiting Trade Agreement (ACTA), a deal signed on January 26 to create international standards for intellectual property protection.
Greece was one of the 22 signatories among European Union states.
Critics of the agreement say it could significantly curtail online freedom.
According to the police, the three youths have been linked to dozens of cyber attacks against Greek websites, using the alias Greek Hacking Scene and the nicknames 'delirium', 'nikpa' and 'extasy'.
They face at least a year in prison if convicted.
Greece is applying a crunch economic overhaul under supervision from the EU and the International Monetary Fund that has left over a million jobless and plunged the country into a deep recession.
Anonymous last month briefly knocked the FBI and Justice Department websites offline in retaliation for the US shutdown of file-sharing site Megaupload and members of the group targeted the CIA website earlier this month.
In late 2010, Anonymous attacked the websites of Amazon, Visa, MasterCard, PayPal and others in retaliation for their decisions to stop working with Julian Assange's anti-secrecy site WikiLeaks.
Explore further: 'SwaziLeaks' looks to shake up jet-setting monarchy