According to a communique seen by The EastAfrican on Wednesday, Igad expressed deep concern over the clashes.
The ministers said the violence has led to loss of life, destruction of property and displacement of civilians in the Upper Nile State.
The regional bloc called upon all factions in the dispute to immediately and unconditionally "cease armed confrontation and refrain from any offensive, provocative or retaliatory utterances, behaviours and other actions that will escalate tensions and hostilities."
The Intergovernmental Authority on Development (Igad) has called on South Sudan’s main opposition party to cease hostilities within its group.
The call comes after Sudan People's Liberation Army–In Opposition (SPLA-IO) soldiers loyal to Dr Riek Machar and those loyal to Machar's former army chief Lt. Gen Gatwech Dual clashed in Meganis village of Upper Nile over the weekend.
SPLA-IO is the military force of Machar's Sudan People's Liberation Movement-In Opposition (SPLM-IO) party.
According to the spokesman of First Vice President Riek Machar, at least twenty-seven soldiers from Gatwech’s faction were killed during the weekend military clashes.
The SPLM-IO generals ostensibly replaced Machar with his previous army chief Simon Gatwech Dual with immediate effect. Dr Machar’s political bureau condemned the move and described the generals behind the plan as peace spoilers.
Ministers from the regional bloc held an extra-ordinary meeting on Monday to discuss the situation.
According to a communique seen by The EastAfrican on Wednesday, Igad expressed deep concern over the clashes. The ministers said the violence has led to loss of life, destruction of property and displacement of civilians in the Upper Nile State.
The regional bloc called upon all factions in the dispute to immediately and unconditionally "cease armed confrontation and refrain from any offensive, provocative or retaliatory utterances, behaviours and other actions that will escalate tensions and hostilities and urged the parties to pursue peaceful avenues of resolution of internal differences and disagreements through dialogue, trust and confidence building and demonstrate greater political will and commitment."
The body requested a monitoring body to investigate these developments and establish the true facts on the ground and report back to the council within seven days.