They had allegedly arranged logistics like transportation and fuel with which the Ashram of Jaggamdora Simhachalam alias Satyanarayana was set on fire, said ASP (Operations) Vishal Gunni.
He said the Ashram was attacked apparently in retaliation to the killing of three Naxals many months ago in a police encounter.
According to police, the militiamen were also involved in snatching of nomination papers from candidates during Panchayat elections last year at Nurmathi and Boithili.
The arrested have been identified as Kotari Laxmaiah (35), Kotari Venkata Raju (25) and Korra Chittibabu (60), residents of Anarba village, and Seendri Appala Raju (29).