The bail applications of Andaluri Eswari (29), Roja Mandini (21), Kendula Sirisha (42) and Gokul Kuldipia (42) were filed.
All the four were arrested from Similiguda on November 13 last year when they were on their way to Narayanpatna in Orissa from Andhra Pradesh in a jeep.
Police had seized Maoist literature, combat uniform and letters written in Telugu to some Maoist commanders from the ultras.
All were booked under Unlawful Activities (Preventive) Act.
Their advocate P K Jena had secured bail yesterday for a senior Maoist leader, Ganti Prasad whose freedom was also demanded by the Maoists during the hostage crisis which ended tonight with the release of Malkangiri Collector R V Krishna.
While the junior engineer Pabitra Kumar Majhi was released yesterday, the Collector was released today evening.
The advocate also filed bail application for another Maoist Gouranga Jena (36), who was arrested by Sambalpur police in June 2008.
It is not known whether Jena`s release was demanded by the Maoists.
All the bail applications are likely to come up for hearing on Friday.