The United Nations said on Monday it was closely monitoring the special court proceedings of South Sudan’s suspended First Vice President Riek Machar and reiterated its call for the trial to meet international standards.

U.N. spokesperson Stéphane Dujarric told reporters in New York that the U.N. peacekeeping mission in South Sudan (UNMISS) was following developments in Juba, where Machar and several allies appeared in court.

“Our mission reminds all concerned that the judicial process must adhere to international standards of fairness and transparency, with full respect for the rule of law and human rights,” Dujarric said.

Separately, Dujarric said the world body was verifying reports of fresh clashes between government forces and armed elements affiliated with the White Army militia in Upper Nile state’s Nasir County. The mission reported casualties and reiterated international calls for an immediate end to hostilities, he added.

The treason trial of Machar opened on Monday morning under heavy security in the capital Juba.

Geri Raimondo Legge, Machar’s lead defense lawyer, said that the court was “unconstitutional and unlawful” because, he argued, Machar retained the immunity of a sitting first vice president appointed under the 2018 peace agreement.

Machar’s SPLM-IO party rejects the charges, which include murder, treason and crimes against humanity for their alleged involvement in attacks by the White Army militia in Nasir County earlier this year.

Seven of Machar’s allies were charged alongside him earlier this month, including the petroleum minister and the deputy army chief

Prosecutor Ajo Ony’Ohisa Igele called the defense’s arguments “weak.”

President Salva Kiir and Machar serve in a fragile transitional coalition government formed as part of a 2018 peace deal that ended the civil war. Radio Tamazuj