Greek terrorist group claims responsibility for Sunday's bomb attack in Athens

ATHENS, Dec. 28 (Xinhua) -- Threatening with more similar attacks in the future, a Greek guerrilla group claimed responsibility on Monday evening for the strong explosion that caused major material damage, but no injuries, at the offices of a Greek insurance company on a main Athens avenue on Sunday night.

"Conspiracy of Nuclei of Fire-Nihilists Sect" acknowledged that it was behind the attack in a statement that was posted on the Internet.

Counter terrorism experts take the claim seriously, noting that until last night this particular group used a different methodology and was responsibly for less serious attacks.

Police experts had suspected another group which has attacked financial targets in the past, like the Athens Stock Exchange building this September.

Now they express fears that "Conspiracy of Nuclei of Fire-Nihilists Sect" which until now had caused minor damages using make-shift bombs in cooking pots, has been upgraded "through cooperation with other comrades" as it is underlined in the statement.

Police are investigating what was left from the explosive device and footage of the security cameras.

Next to the insurance company's offices there is a cinema that had to be evacuated.