While the two sides violated the cease-fire dispute that had signed the Peace Package last week included a ceasefire that took effect on Saturday was the second attempt by regional mediators to try to end the war after a deal in 2015 failed.
Lul Ruai Koang, spokesman for the government military SPLA said rebels attacked Maban in Upper Nile state in the far northeast near the border with Sudan on Sunday.
He said, rebels killed 18 civilians and wounded 44, the dead included three Ethiopians and two Sudanese.
Lam Paul Gabriel, deputy spokesman for the opposition SPLA-IO said their forces had been heavily bombarded by the military in the Maban area on Sunday and denied attacking civilians, saying: It is not the policy of SPLM-IO to attack civilians.
South Sudan was plunged into war in 2013 after a political disagreement between President Salva Kiir and his former vice President Riek Machar exploded into a military confrontation.
