The UN humanitarian agency on Friday called for safety of civilians and aid workers amid intensive fighting in South Sudan.

"All parties to the conflict have a responsibility to make sure that civilians are spared from the fighting, do everything possible to restore calm, and ensure that law and order prevails," Humanitarian Coordinator in South Sudan Toby Lanzer said in a statement.

Lanzer said aid agencies has required 166 million U.S. dollars from the international donor community to enable them to respond to humanitarian situation in the world's newest state.

"This is the time to stand with the people of South Sudan and over the coming days and weeks we will do all we can to do just that," he said.

He said violence in South Sudan over the past two weeks has displaced around 200,000 people and affected hundreds of thousands of civilians indirectly.

Lanzer said aid agencies are scaling up their work, especially in towns most heavily struck by violence and in rural sites to which civilians have fled in order to seek safety.

There are reports that the rebels were approaching the capital Juba, although negotiators from both sides have started peace talks in neighboring Ethiopia.