Fighting has been witnessed in the last four months in the oil-producing states of Unity and Upper Nile.

A deal between the government and opposition groups signed this month on the sharing of key positions in the army and security forces has so far failed to end the fighting, according to the mining minister.

“The situation has not yet improved, the parties continue to fight. Investigations are needed," Maj Gen Martin Gama Abucha told the monitors during a meeting in the capital, Juba.

"From 21 March to date, insecurity and human rights violations continue,” he added.

On Monday, the UN peacekeeping Mission in South Sudan (Unmiss) reported that at least 72 civilians were killed, including some who were burnt alive and decapitated in Leer County in Unity State.