Greek anti-terrorist police have raided at least two suspected hideouts of domestic terrorists, detaining seven people and seizing weapons and disguises, authorities said.
Officers confiscated two automatic assault rifles, six handguns, a revolver, police uniforms, wigs, computers and radios in the raids in the central city of Volos and in Athens, while more swoops were being conducted in other parts of the capital.
Four men and a woman were detained for questioning in the Volos operation, and a man and a woman in Athens, police said.
Far-left militant and armed anarchist groups have been active in Greece for decades. But attacks have increased in the past two years, despite the arrest of more than a dozen suspects, following the fatal police shooting of a teenager in Athens in December 2008 which led to widespread riots across the country.
The latest spate of attacks was a series of letter bombs, most of them sent to foreign embassies in Athens in November.
The booby-trapped packages included one which made it to German chancellor Angela Merkel's office in Berlin and another addressed to Italian premier Silvio Berlusconi. The latter caught fire on board a courier flight which had landed at Italy's Bologna airport.
Another letter bomb was sent to the Justice Ministry in Athens in February. None caused any injuries.
A militant anarchist group, Conspiracy Nuclei of Fire, has claimed responsibility for the letter bombs.
Nine suspected members of the group, mostly in their early 20s, went on trial in January over the attacks and four others are being tried in their absence.
The process is expected to take several months.