Two members of the police's motorcycle-riding rapid response unit DIAS are believed to have participated in protection rackets that the Attica Security Police's extortion division dismantled last week.
One of the pair is alleged to have taken part in the beating of a driver of a tourist bus, an act paid for by a rival travel group, according to sources.
The second suspect is thought to have planted a homemade explosive device in a bar in western Attica in a bid to take revenge for the firing of a colleague who had been employed there.
A police crackdown led to a total of 19 suspected members of two crime rackets thought to have been selling protection to Attica store owners while another 11 are being sought.
Most of the suspects are Greek nationals with the alleged ring-leaders thought to be two Greek men, aged 59 and 51, who have been detained on various charges in the past.