UN Mission in South Sudan, UNMISS condemned what it described unprovoked attack on a convoy of barges hired to deliver urgently needed food and fuel supplies to its base in Malakal.
In a statement, the Mission said the attack took place on the Nile River near Barbuoui.
The Mission added that it was set to establish the identity of the assailants, saying spokespersons for SPLA and SPLM/A in Opposition forces denied any responsibility for the attack.
The statement indicated that none of the conflicting forces was present in the area where the attack took place.
Rocket-propelled grenades were fired at the convoy of four vessels and four crew members and UNMISS peacekeepers were wounded during the incident.
The convoy left the Central Equatoria State town of Mangalla on April 18 with 16 crew members and 56 UNMISS peacekeepers aboard, resuming its voyage towards Malakal early Thursday morning.