BARCELONA, Spain (AP) 鈥� South Sudan鈥檚 armed opposition on Sunday accused government troops of violating a cease-fire just hours after it came into effect.

A statement by opposition spokesman Lam Paul Gabriel said government troops have been 鈥渂ombarding鈥� opposition positions in Yei county and launched an attack in Koch county Sunday morning that opposition forces 鈥渞epulsed.鈥�

Gabriel said government troops also were en route to launch another attack in the Wau area. 鈥淚t is a matter of time before they reach our positions,鈥� he said.

These are the first reported violations of the cease-fire that went into effect just after midnight. The warring sides agreed to the cessation of hostilities on Thursday after days of internationally mediated talks in neighboring Ethiopia.

South Sudan government spokesman Ateny Wek Ateny told The Associated Press that 鈥淗ow can we violate the cease-fire? It just went into effect. ... We can only fire back in self-defense.鈥�

The East African country is entering its fifth year of civil war. No one knows how many tens of thousands of people have been killed. Parts of the nation are on the brink of starvation and two million people have fled to neighboring countries.

Earlier this month, the UN Security Council warned of 鈥渃osts or consequences鈥� for South Sudan鈥檚 government and opposition if they undermine efforts to implement the 2015 peace deal. Consequences could include further sanctions.

Under the new agreement, the warring sides also committed to grant badly needed humanitarian access to conflict-affected areas and to release prisoners of war, political prisoners and abducted women and children.

South Sudan plunged into ethnic violence in December 2013, just two years after a long-fought-for independence from Sudan, when forces loyal to President Salva Kiir, a Dinka, started battling those loyal to his former vice president, Riek Machar, a Nuer.

The UN and others have warned against ethnic violence and other abuses, including the recruitment of children as soldiers and the widespread use of sexual violence as a weapon of war.