MANILA (UPDATE) - Militant groups on Friday condemned the alleged abduction and illegal arrest of Kilusang Mayo Uno (KMU) organizer Marklen Maojo Maga.

Staging a protest outside Camp Crame in Quezon City, the groups called for the immediate release of Maga, National Democratic Front of the Philippines peace consultant Rafael Baylosis, and all political prisoners.

Militant groups call for immediate release of NDFP consultant Rafael Baylosis, KMU organizer Marklen Maojo Maga, other political prisoners @ABSCBNNews pic.twitter.com/W9RcPimjW0

— Bianca Dava (@biancadava) February 23, 2018

"Itong hakbang ng rehimeng Duterte ay pagpapakita na talagang ang crackdown sa hanay ng mga legal organization tulad namin ay isinasagawa na," KMU Secretary-General Jerome Adonis said.

"Ayaw ni Duterte na harapin ang mga lehitimong kahilingan ng mga manggagawa," he added.

Maga was allegedly abducted by policemen in civilian clothing at a basketball court near their house in San Mateo, Rizal on Thursday morning.

His family and lawyers got the confirmation only later that night that he was being held at the Philippine National Police-Criminal Investigation and Detection Group (PNP-CIDG) office at Camp Crame, Adonis said.

"Walang ipinakitang warrant of arrest sa kanya. Napuntahan lang namin sya kagabi ng mga alas nueve at hinanapan ang CIDG ng warrant of arrest, pero wala silang napresent," Adonis said.

"Ang sinasabi nila, kinargahan nila ng baril at may murder case, pero maski don, walang maipakita sa aming kasamahan... Nagfa-fabricate na sila," he added.

The PNP-CIDG said Maga was arrested on the strength of an arrest warrant issued by Cabadbaran City, Agusan del Norte Regional Trial Court Branch 34 Judge Cesar Bordalba for his alleged involvement in the murder of a soldier in March 2017.

He has been charged before the Department of Justice (DOJ) Friday for illegal possession of a firearm and ammunition after police allegedly found a .45 caliber pistol and a magazine loaded with 7 bullets in his possession.

• Leftist labor group organizer charged for gun possession

Before becoming a KMU organizer, Maga used to be an active member of the League of Filipino students. He was also a founding member of the youth group Anakbayan.