South Sudan rebel leader Machar arrived in the Ethiopian capital on Friday for direct talks with Kiir sought by UN Secretary-General Ban Ki-moon and US Secretary of State John Kerry.

Earlier this week, a UN peacekeepers' report and Amnesty International accused the Sudanese rivals of letting their power struggle degenerate into ethnic Nuer and Dinka atrocities and forced displacements.

Machar arrived in Addis on Thursday. Kiir arrived Friday morning, local time, according to officials in his delegation. The European Union - one of the biggest donors of development aid in South Sudan - said Friday it was considering sanctions against those responsible.

A spokesman for Machar said the two leaders would be unlikely to meet immediately. Both men, he said, would first hold talks first with host and top mediator, Ethiopian Prime Minister Hailemariam Desalegn.

Fear of irreversible damage

An EU diplomat was quoted by the news agency AFP as saying that no decisions had been taken "so far," but the possibility would be discussed next week.

The news agency Reuters said the US had already imposed asset freezes on two rival subordinates: Peter Gadet, an commander loyal to Machar, and Marial Chanuong, the head if Kiir's presidential guard.

The head of the UN mission in South Sudan said the violence of recent months had put Africa's youngest country "back decades," adding that the damage would be irreversible if it did not stop soon.

More than a million people have been displaced by the bloodshed, despite a ceasefire agreement reached in January.

As Kiir arrived in Addis, rebel military spokesman Lul Ruai Koang claimed that forces aligned with Kiir were "attacking our forces" in three South Sudanese regions.

Famine threat looms

The UN report published Thursday and based on 900 interviews cited extrajudicial killings, enforced disappearances, rape, the targeting of civilians - often along ethnic lines - as well as the destruction of property.

Aid agencies have warned that South Sudan is on the brink of Africa's worst famine since the 1980s.

The conflict, which started as a personal rivalry between Kiir and Machar, has seen the army divide along ethnic lines, pitting members of Kiir's Dinka tribe against Machar's Nuer.

Violence erupted in mid-December, when Kiir accused Machar of attempting a coup. Machar said Kiir had instead attempted to purge his rivals.

ipj/rc (AFP, dpa, Reuters)