Two people believed to be involved in attacks orchestrated by the guerrilla organization Conspiracy of the Cells of Fire were being questioned by counter-terrorism officers in Athens on Friday following their arrest in Thessaloniki.

The two men, both aged 30, are being probed in particular for their possible involvement in a suspected spinoff organization, Informal Anarchist Federation-International Revolutionary Front, which claimed responsibility for mailing a booby-trapped envelope to the former head of the country's anti-terrorism unit Dimitris Horianopoulos and for bombing the cars of the Korydallos Prison Governor and of a jail guard in Nafplio as well as other attacks.

The letter bomb to Horianopoulos was intercepted and destroyed in a controlled explosion.

The two suspects were to face a prosecutor on Friday afternoon.