The African Union (AU) has urged action regarding the situation in South Sudan, where a recent ceasefire agreement between feuding parties collapsed soon after it was reached.

AU Chief Moussa Faki Mahamat called on African leaders at a gathering in Nouakchott, the capital of Mauritania, on Saturday to take measures against South Sudan’s President Salva Kiir and rebel leader and former vice president Riek Machar — who lead the two sides of the conflict in South Sudan.

In the Sudanese capital, Khartoum, on Wednesday, Kiir and Machar signed an agreement on a “permanent” ceasefire to take effect within 72 hours.

“The situation in South Sudan is serious. The humanitarian and security situation is increasingly difficult. The last few days we’ve had some good news, which I unfortunately now have to question,” Mahamat said.

“We are used to them not respecting their commitments,” he said, referring to Kiir and Machar. “[The] situation is intolerable... It is time to act, to accept our responsibility.”

He said action could include possible sanctions.

“We have to send a clear message to the players to respect their commitments,” he said.

The ceasefire raised hopes for an end to the five-year-old civil war that engulfed the world’s youngest country only two years after its independence from Sudan in July 2011.

The government forces and rebels, however, launched attacks on each other’s positions on Saturday, just hours after the ceasefire went into effect.

The rebels claimed that the army attacked their positions in the northwestern village of Mboro near the border with Sudan. The attacks were “provocative aggression aimed at derailing the peace process,” said rebel spokesman Lam Paul Gabriel.

Rebels led by Machar have said they “reserve the right to self defense,” according to Gabriel.

The government, on the other hand, said the rebels launched coordinated attacks on the army positions in four states, to gain more territory before the permanent ceasefire.

Several former peace agreements have similarly broken down, and the war has uprooted nearly four million people and killed tens of thousands.