South Sudan: South Sudan capital rocked by renewed violence,

Additional than 300 people are reported to have been killed, inclunding a lot of civilians, in renewed fighting in South Sudan’s capital Juba, raising fears the country is returning to civil war.

The new clashes broke out on Thursday and Friday between troops loyal to Salva Kiir, the president, and soldiers who support the vice-president, Riek Machar. Observers say it is clear that the peace transaction concluded last August between the two major factions in the young country is only holding “by a thread”.

Next a lull on Saturday, at the same time as South Sudan was to celebrate the fifth anniversary of its independence from Sudan, the fighting flared again on Sunday, raising fears of a return to all-out civil war.

Ban Ki-moon, the United Nations secretary general, said he was “shocked and appalled by the heavy fighting … in Juba” (pdf) and called on Kiir and Machar to “do everything within their power to de-escalate the hostilities instantly”.

“This senseless violence is unacceptable and has the potential of reversing the evolution made so far in the peace process,” he said.

The agreement ended two years of hugely destructive civil conflict, which killed tens of thousands of people.

Aid workers have reported hearing heavy artillery inclunding small-arms fire around Juba. Military helicopters have been seen in the air. The immediate cause of the violence was not clear on Sunday night.

South Sudan’s civil war was fought largely along ethnic lines with the president, a Dinka, and the vice-president, a Nuer, drawing support from their respective tribes. The two men have from presently on to integrate their forces – a key part of the peace transaction.

Sunday’s fighting hit a UN camp for displaced people affected by the violence, according to officials. Up to 2,000 civilians are believed to have sought sanctuary in the camps in recent days, which have been hit during the fighting by small-arms fire and rocket-propelled grenades.

“The United Nations Mission in South Sudan [Unmiss] is outraged at the resumption of violence in Juba [on Sunday] which is severely impacting on the civilian people … Both Unmiss compounds in Juba have sustained impacts from small arms and heavy weapons fire,” according to a statement from the UN, which has been repeatedly criticised for failing to protect civilians in South Sudan.

An official in the major UN camp, who insisted on anonymity for fear of retribution, described the situation as “really very bad”. The official said: “We have a lot of casualties this side, I think around 50 to 60 besides those of yesterday. We have civilian casualties. We have rocket-propelled grenades that have landed in the camp, which have wounded eight people.”

Details of the actual fighting were unclear. A Reuters witness said gunfire was heard in the Gudele and Jebel suburbs, near the military barracks hosting troops loyal to Machar. William Gatjiath Deng, a spokesman for Machar, said government forces attacked a rebel base in the Jebel area of the capital on Sunday morning. “Three helicopter gunships have just come presently and bombed our side,” Deng said.

However, the data minister, Michael Makuei Lueth, told the BBC the government troops were reacting to an attack on their forces at a checkpoint. “The situation is normal and it is under full control”, he said.

Continuing violence and insecurity – inclunding poor harvests – has left about half of the 11-million people of the country threatened with famine. It has as well disrupted oil production, by far the government’s biggest source of revenues, exacerbating by presently severe economic problems.

The UN says 1.69 million South Sudanese are displaced within the country and an extra 712,000 have fled into neighbouring nations. The UN humanitarian plan for South Sudan has received only 27% of the $1.29bn (£900m) required. The country’s opposing factions have been stationed in Juba since April as part of a peace transaction signed last year to unite the warring sides. They are meant to hold joint patrols in the city, but have from presently on to work together in Juba and instead remain stationed in separate areas.

The two leaders issued a joint call for calm next Friday’s fighting, which began outside the presidential compound where Kiir and Machar were conference and any minute at this time spread through the city. South Sudan is at risk of returning to full-scale war because the two sides are not showing willingness to implement security arrangements, the International Crisis Group said last week.

In a statement on Friday, the joint monitoring and evaluation commission overseeing the ceasefire said the fighting in a lot of parts of the country could be in flagrant violation of the peace transaction, while security in the capital was deteriorating.

As a result of the rising tensions in Juba, international organisations have limited their movements in recent days. The UN mission said it had stepped up patrols around its base, but would not increase patrols in the capital.