Reports by United Nations said South Sudanese rebels have once again clashed with government troops in efforts to gain control over the northern town of Nasir. The fresh offensive is said to be the largest since May, when the rebels and the government last violated a ceasefire brokered in Addis Ababa.

UN spokesman Joe Contreras said the new offensive "represents the most serious resumption of hostilities" since South Sudanese President Salva Kiir and his former deputy turned rebel leader Riek Machar, promised again in May 9, to stick to a January ceasefire.

Simona Poltyn, a journalist working in Juba, told DW that the offensive could represent the first in a series of attacks to try and reclaim control over territories lost during the previous months of fighting.

"Nasir, has a symbolic and strategic importance for the rebels because it is the home town of Rieck Machar," she said.

There was also an increase in the number of armed groups and some of them wereacting more or less autonomously. Poltyn believes this makes the situation on the ground difficult to control.

Confirming the new clash, rebel spokesman Lul Rual Koang told Reuters news agency that there has been shelling in Nasir town but denied that the rebels were control of the town. "The rebels don't control Nasir," he said.

Other reports say that Nasir, which has been changing hands, since the fighting started in December, is now under the rebel control.

Lasting peace deals

Efforts to bring the two warring parties to the negotiating table and to come up with a sustainable peace deal have met with little progress.

For months now representative from both sides have been meeting in Addis Ababa, trying to hold talks to end the crisis, but nothing substantial has come out of the meetings.

Last week, Ethiopian Prime Minister Hailemariam Desalegn, who heads the East African bloc, IGAD, which is mediating the peace talks, told the two warring parties that time was running out.

"For every negotiation there is a limit, you cannot continue forever. When we believe it has come to a dead end then we have to do something else," Desalegn said.

Last months IGAD threatened both sides with sanctions if the May peace deal was violated. They told them to form a transitional government and implement a ceasefire agreement by August 10.

To help resolve the crisis, the European Union and the United States have imposed sanctions on two military leaders, one from each side.

'Self-serving elite'

According to the UN the conflict has killed thousands and displaced 1.5 million people. Some have found refuge in UN camps, others continue to endure the harsh conditions in the bush. Humanitarian agencies have warned of a famine if the fighting continues.

Earlier this month, departing UN representative in South Sudan Hilde Johnson, accused the country's leaders of belonging to a "self- serving elite" which she believes that was responsible for a looming "man-made famine."

Desalegn also made a similar accusation by saying that lack of commitment by the leaders was stalling progress in the peace process. They weree responsible for South Sudanese people's suffering.

"[Leaders] should think about the people and come back to the negotiating table as quickly as possible," said Desalegn.