World Bulletin / News Desk
The army on Sunday accused the rebels of opening fire near Malakal town in the newly created Fashoda State on Friday.
South Sudanese army spokesman Brigadier Lul Ruai Koang accused pro-Machar forces led by Gen. Johnson Olony of attacking in Warjuak and Leleo, about 20 kilometers (12 miles) north of Malakal.
The two sides had agreed a ceasefire in July after a renewed flare-up which left at least 300 people dead.
President Salva Kiir and Machar had formed a unity government in April aimed at ending almost three years of brutal civil war. However, the fresh clashes in July sparked concern for the hard-won peace deal.
Almost 2.5 million people fled their homes in over two years of civil war marked by ethnic killings, gang rapes and the use of child soldiers. Some 200,000 civilians are sheltering inside UN bases within the country.