ATHENS (AP)  A Greek radical anarchist group has threatened to blow up judges officiating over the trial of suspected group members as it claimed responsibility on Wednesday for a powerful blast outside an Athens courthouse. The Dec. 30 court bombing severely damaged the building and parked cars, but caused no injuries as police had evacuated the area after a warning call. "From now on, their (the judges) personal safety is in direct jeopardy," Conspiracy Nuclei of Fire said in an online posting on a left wing website on Wednesday. "We publicly pledge that, for every year in prison that our brothers receive, we will plant a kilo of explosives in (judges') front yards, cars and offices." The suspected group members are due to be tried on Jan. 17 on terrorism charges for a string of bombings against Greek politicians. Nobody was hurt in the attacks. Nine youths are to appear in court, inside a maximum-security Athens prison, and another four will be tried in absentia. The group also referred to the judges in the posting as "latter-day members of the Holy Inquisition." Conspiracy Nuclei of Fire has also claimed November's parcel bomb campaign against Athens embassies that caused no injuries or damage. Booby-trapped packages were also addressed to European heads of government, and one reached the office of German Chancellor Angela Merkel before being destroyed. In Wednesday's posting, the group repeated calls for worldwide attacks by radical anarchists ahead of the trial. A similar appeal last year sparked copycat parcel bomb attacks in December on embassies in Rome, which injured two people and prompted Greek and Italian authorities to investigate links between extremists in both countries. The online proclamation was signed as "Conspiracy Nuclei of Fire — Commando Horst Fantazzini," whom the group identified as a bank robber who died in an Italian prison in 2001. Copyright 2010 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more