South Sudan’s rival military leaders said on Wednesday that Vice President Riek Machar has been dethrone as head of his party and its armed forces, a move that could pressure an already fragile peace process.

Machar played a vital role in pushing his partner, President Salva Kiir, to a peace deal in 2018 and in the subsequent formation of a unity government following years of civil war.

But he was stripped of party posts after a three-day meeting of senior leaders of his SPLM/A-IO movement who accused him of undermining reforms and giving family members strategic posts, said a statement from the party’s military wing.

Machar’s wife Angelina Teny serves as defence minister.

His party’s spokesman in the capital Juba, Lam Paul Gabriel, said there would be a response later in the day.

First Lieutenant General Simon Gatwech Dual, the party’s chief of staff, was named interim party leader, according to the military wing’s statement.

South Sudan gained independence from Sudan in 2011 but descended into fighting two years later when forces loyal to Kiir and Machar clashed in the capital.

That sparked the massacre of hundreds of civilians in Juba from Machar’s Nuer ethnic group and a spiral of brutal ethnic violence and revenge killings.

The civil war killed 400,000 people and triggered Africa’s biggest refugee crisis since the 1994 Rwandan genocide.

With the army still divided and some militia groups refusing to sign the peace deal, the latest split in Machar’s movement could undermine stability, said James Okuk, a senior researcher at the Juba-based Center for Strategic and Policy Studies.

“The agreement has been very slow and part of the reason is the obstruction of these generals on the ground,” he said.