The crisis in South Sudan is almost as old as Africa itself, a confused ­confrontation between tribal rivals in what is already an ethnically divided country, with claim and counter-claim being made and no-one any the wiser about what is actually happening.

Mix in lavish oil wealth - the vast bulk of South Sudan's income comes from oil revenue - and the presence of weapons from the last round of civil war in 2011 and the whole region is a tinderbox. So far an estimated 500 people have been killed in the fighting, but the true figure could be much higher.

What little is known is ­predictable and deeply ­dispiriting. During the summer President Salva Kiir, a member of the ­majority Dinka ethnic group, sacked his deputy Riek Machar, from the Nuer community, following an alleged coup attempt. The move heightened tensions and the flashpoint came a week ago in the capital Juba when uniformed personnel opened fire at a meeting of the governing party, the Sudan People's Liberation Movement (SPLM), amid rumours the presidency was under threat.

This was enough to spark further violence that quickly flared across the country, with gangs of armed Nuer and Dinka youths fighting each other. In the mayhem that erupted, thousands of people, many of them oil workers, attempted to flee the violence by taking refuge in compounds guarded by government and UN peace-keeping forces, but the havens were illusory. At the end of a week of casual violence, two blue-bereted UN Indian Army soldiers were killed and at least a dozen civilians gunned down. ­Fighting has also been reported in Pibor, 200 miles north-east of Juba, and there are fears the populous province of Jonglei could also be drawn into the conflict

Yesterday attempts were still being made to create some dialogue between the two rival sides, and US Secretary of State John Kerry despatched a special envoy in the shape of experienced ambassador Donald Booth, but the chances of an immediate breakthrough are slim. President Kiir claims to want unconditional dialogue to resolve the issue and on Friday there was a feeling a solution could be in offing when he met diplomats from Ethiopia and Kenya, who were in the country attempting to broker a deal. However, those hopes evaporated when Machar told French diplomats there could only be a solution if his Dinka rival stands down, which is unlikely to happen.

This weekend's violence is unlikely to be contained before the year comes to an end, and South Sudan is odds-on favourite to present the world with its first ­serious emergency for 2014.

South Sudan only achieved independence two years ago and the Kiir-Machar partnership was supposed to provide the glue that would keep the country together. Diplomats now fear that unless the current unrest is brought under control South Sudan will once again be plunged into a bloody civil war, just as it was twice in the past, between 1955 and 1972 and then again from 1983 until 2005. Conservative estimates put the death toll from both conflicts at three million.

An added complication is the ­presence of Sudan to the north. Not only do the oil pipelines run through its territory but the bulk of the population is of Arab descent and they look down on the mainly African southern areas. If South Sudan's oil fields fall into rebel hands this could provide the reason for an extension of the violence, with Sudanese forces deployed to protect the oil fields. In the past differences have been patched up by negotiation, but with vice-president Machar on the run and seven of his ministerial rivals arrested the room for manoeuvre is limited.

There has also been a change of perception. Last week President Kiir appeared on state television and denounced his rival as "a prophet of doom".

In a little noted move, the US despatched a small special forces team to Juba to protect lives and property while President Barack Obama gave a sombre warning that the country "stands at the precipice". He added: "Recent fighting threatens to plunge South Sudan back into the dark days of its past." The stakes are already high and they are clearly getting higher.