ATHENS, Greece (AP) — Police in Greece say two 30-year-old men have been arrested in northern Greece as suspects in a recent bombing campaign claimed by anarchist militants.

Police spokesman Christos Parthenis said Friday that the men were arrested late Thursday in the city of Thessaloniki and detained for questioning. Their arrest is in connection with a July 7 bomb attack against the head warden of an Athens prison, and a failed parcel bomb attack on July 3 against a former senior anti-terrorism official. No one was hurt in either incident.

The attacks were claimed by the Greek group Conspiracy Nuclei of Fire, or SPF, and the Informal Anarchist Federation, or FAI, considered an umbrella group for mostly European anarchist and far-left militants.

Similar groups have been active in Greece since the 1970s.