Story highlights

The attack occurs in oil-rich Unity State, says a South Sudan government spokesman

The government says the attackers were part of the South Sudan Liberation Army

The rebels say they are fighting corruption and domination of the Dinkas

South Sudan became a nation in July, separating from Sudan

CNN  — 

South Sudanese rebels launched an attack in oil-rich Unity state that killed 39 people, a spokesman for that fledgling government said Saturday.

Yein Matthew, the government spokesman, said the attacks in Mayom were carried out against civilians by militias of the South Sudan Liberation Army.

South Sudanese government forces were pursuing the attackers through nearby woods, according to Matthew. One militia leader has been captured and is being questioned.

Liberation army members have clashed with the military of South Sudan, which separated from Sudan and became independent in July.

Since then, the world’s newest nation has been challenged by a number of rebel militias. Led by former officers of the southern army that fought Khartoum in a 22-year civil war, the militias have taken up arms against their former comrades for various reasons.

The South Sudan Liberation Army, for instance, has said that it is fighting corruption and domination of Dinkas, the new nation’s main ethnic group.

South Sudanese President Salva Kiir has offered amnesty deals to the rebels. Several truces have not been honored, according to the Enough Project, which seeks to end genocide and crimes against humanity.

CNN’s Brian Walker contributed to this report.