By Carl Odera
JUBA (Reuters) - African mediators sought on Saturday to meet rivals to South Sudan's president in a bid to end fighting that threatens to drag the world's newest country into an ethnic civil war.
Hundreds of people have been killed in nearly a week of clashes that spread from the capital Juba and have reached vital oilfields, deepening the most serious internal crisis since the state won independence from Sudan two years ago.
President Salva Kiir, of the Dinka ethnic group, has accused his former vice president Riek Machar, a Nuer who was sacked in July, of trying to seize power.
Although Juba, the capital, was calm on Saturday, United Nations staff say hundreds of people have been killed across the country the size of France and 35,000 civilians are sheltering at their bases.
The United States was instrumental in securing South Sudan's independence. In a sign of its concern, U.S. Secretary of State John Kerry said he was sending an envoy to help talks.
On Friday, African mediators met President Kiir for what they called "productive" talks. His government said on its Twitter feed it was willing to hold talks with any rebel group.
South Sudan's foreign minister, Barnaba Marial Benjamin, said the mediators had now been given the go-ahead to meet with Kiir's rivals, including Machar and his allies.
"Let them also get confirmation from them that they are willing to dialogue," Benjamin told Reuters by phone, adding that Kiir would have no problem speaking to Machar.
On Saturday, the mediators were to meet Machar's family and would also make contact with Machar, Benjamin said.
Information Minister Michael Makuei Leuth told Reuters that Machar was in Bentiu, capital of the oil-producing Unity State, where soldiers from rival factions clashed at a barracks this week. The information could not be independently verified.
The mediators - who include African ministers and an African Union official - would leave for the Ethiopian capital, Addis Ababa, on Saturday.
U.S. envoy for Sudan and South Sudan, Ambassador Donald Booth, is also being sent to help facilitate talks.
The United Nations said on Friday at least 11 people from the ethnic Dinka group had been killed during an attack by thousands of armed youths from another ethnic group on a U.N. peacekeeping base in Jonglei state. Two Indian peacekeepers died.
Army spokesman Philip Aguer said on Saturday that helicopter gunships had raided the rebel-held town of Bor, 150 km (90 miles) north of Juba. He gave no further details.
(Reporting by George Obulutsa; Editing by Matthew Tostevin)