The new American director of the World Food Program called the suffering in South Sudan's famine "deplorable" as he visited the country and called on the government to allow aid groups safe access.

"We want to feed the hungry children and the innocent civilians," David Beasley told The Associated Press before departing Tuesday for the affected area. "If you let us do our job, we'll get it done."

South Sudan's civil war is now into its fourth year, with farming and markets disrupted and food prices soaring. Both violence and harassment have slowed aid efforts.

"Seeing innocent children and families suffer because of this man-made conflict is absolutely deplorable," Beasley said.

His visit came a day after President Salva Kiir again called for a unilateral ceasefire to go into effect immediately. It requires all soldiers to stop attacking rebels. Kiir also promised to release political prisoners, but there was no immediate sign of any deal struck with the opposition.

"This is being done for the purposes of paving the way to invite everyone to participate in the national dialogue" set to start next week, said military spokesman Col. Santo Domic Chol.

The United Nations welcomed the prospect of a ceasefire and release of prisoners but stressed the importance of better access for peacekeepers and humanitarian workers.

"The long-term peace and stability in South Sudan can only be achieved through an inclusive political process which is deemed credible by the people of South Sudan," said Daniel Dickinson, spokesman for the U.N. mission there.

Beasley said humanitarian funding could run out by October if aid workers can't reach those in need. He called that prospect catastrophic.

The U.N.'s humanitarian appeal for South Sudan calls for $1.6 billion to assist 5.8 million people in 2017. It's 46 percent funded so far.