U.S. Secretary of State John Kerry is trying to arrange direct talks between South Sudan's president and the leader of rebel forces in hopes of ending the country's escalating violence.

Kerry arrived in the capital, Juba, on Friday and met for more than an hour with President Salva Kiir. He said afterward that Mr. Kiir is willing to travel to peace talks in Ethiopia next week that would "hopefully" involve rebel chief and former vice president Riek Machar.

He said he planned to talk to Machar by phone later in the day.

The secretary called on both men to condemn ethnically-motivated attacks on civilians. Kerry is also trying to negotiate a deal to send African Union peacekeepers as soon as possible to help stop the fighting and protect civilians.

Fighting erupted across South Sudan in December after Mr. Kiir accused Machar of attempting a coup.

The violence has killed thousands and displaced more than one million people.

The U.S. has threatened sanctions against those responsible for the violence.

Kerry is on a multi-nation tour of Africa that has largely focused on security and human rights issues.

While in the Ethiopian capital Thursday, Kerry said the United States supports African-led efforts to combat "the most deadly conflicts of the continent." He said too many nations are at risk of descending into broad-based violence.

"It is clear that the unspeakable violence in the Central African Republic, the deliberate killing of civilians on both sides in South Sudan, both of those underscore the urgency of the work that we have to do together."

On Thursday, Kerry held talks with AU officials on the Central African Republic where Muslims continue to flee their homes to escape attacks by Christian militia.

After returning to Addis Ababa, Kerry is due to meet with Somali President Hassan Sheikh Mohamud to discuss the fight against the al-Qaida-linked militant group al-Shabab.

On Saturday, he travels to the Democratic Republic of Congo's capital to meet with President Joseph Kabila. The two will discuss recent security gains against rebel groups in volatile eastern Congo.

After a stop in Angola, Kerry returns to Washington on Monday.