An explosion occurred outside the Appeals Court in Thessaloniki on Friday, but no injuries were immediately reported. The building had been evacuated after warning calls to a newspaper and television station. Police have cordoned off the area

It was the second bombing in two days - after a blast Thursday outside a jail in Athens that also wounded one person - raising concern that a recent crackdown on Greek militant groups could spur a new series of attacks.

Police had evacuated most of the court building after a Greek newspaper and television station received an anonymous call warning that a bomb had been planted in the toilets in the building's basement. Dozens of people inside the building were seen running out the court moments before the blast.

Police said the blast knocked down some walls inside the building. A police investigator, who asked not to be identified because he is not authorized to talk to the media, described the damage to the lower part of the building as 'extensive.' Court officials said the building will be closed Monday and Tuesday.