Thousands of demonstrators took to the streets on Saturday in a stronghold of South Sudan’s main opposition party, calling for the release of First Vice President Riek Machar, who is currently suspended and facing trial over his alleged involvement in a deadly militia attack.

Machar, 73, is accused in a special court of orchestrating the March assault on an army base in Nasir County, which authorities say left over 250 soldiers dead. He has been under house arrest in Juba since March 26.

Protesters and local officials in Nyirol County, Jonglei State, a stronghold of the Sudan People’s Liberation Movement-in-Opposition (SPLM-IO) and part of the Lou Nuer community, condemned the trial as a politically motivated “witch-hunt.”

“The protest was peaceful. The civil population is demanding that Machar and the other co-accused be released,” said resident John Both.

Another demonstrator, Both Jal, questioned the impartiality of the domestic judicial process. “What is happening in Juba is politically motivated. If anything, we want the accused to face trial in a neutral international court,” he said.

Peter Gatkuoth Koang, the SPLM-IO-appointed commissioner for Nyirol County, confirmed that he had authorized the protest as a constitutional right. He also raised concerns about the lack of transparency in the trial process.

“First, the detention and trial of our officials are politically motivated. We demand their release,” Koang said. “We are also concerned about the cancelation of live court broadcasts, which we see as a potentially illegal maneuver.”

Saturday’s protest marks the second major public demonstration over Machar’s detention. Last month, thousands of residents at an internally displaced persons camp in Bentiu held a similar protest and submitted a petition to the United Nations mission calling for his release.