They are presently lodged in the Central Jail here.
The orders to detain them under NSA were signed by District Collector Archana Patnaik on the recommendations of Q Branch Police, which is investigating the cases.
Police said copies of the order were today served on the Maoists at the jail. Under NSA, they cannot come out on bail for a year.
The Maoists were arrested near Karumathampatti, about 25 km from Coimbatore, on May 4.
The arrests were made by Andhra police after a joint operation by Andhra, Kerala, Karnataka and Tamil Nadu police.