JUBA, South Sudan (AP) — South Sudan's warring factions say violent clashes are continuing before a cease-fire is to come into effect on Sunday.

Joe Contreras, spokesman for the U.N. mission in South Sudan, confirmed there was an exchange of fire Friday night.

The government on Saturday accused rebel forces of attacking its positions in Malakal, the capital of war-torn Upper Nile state, on Friday night as well as Saturday morning.

South Sudanese military spokesman Col. Philip Aguer said a soldier was wounded when rebels shelled Malakal Friday night, forcing government troops to respond with fire.

Rebel spokesman James Gatdet Dak blamed the government for instigating the attack.

South Sudan's warring sides signed a peace agreement calling for a cease-fire to begin Sunday. The factions have previously signed many cease-fires that have been quickly violated.