KHARTOUM, May 4 (Reuters) - A top tribal leader allied to South Sudan was killed in clashes involving a rival Sudanese tribe in the Abyei region disputed by the African neighbours on Saturday, both sides said, an incident that risks fuelling new tensions in the flashpoint area.
Abyei, straddling the border between Sudan and South Sudan, is claimed by both sides, which fought one of Africa's longest civil wars.
In March, both countries agreed to resume cross-border oil flows and defuse tensions which have plagued them since South Sudan's secession in 2011 after an independence vote.
But they were unable to decide on the ownership of Abyei, which is inhabited by the Dinka tribe allied to South Sudan and the Misseriya, an Arab tribe following Sudan.
Kuwal Deng Mayok, the top Dinka leader in Abyei, was killed by members of the Misseriya, another Dinka leader told Reuters, asking not to be named.
"The Misseriya targeted him after he had held a meeting in Abyei town with Misseriya leaders," he said. "The Misseriya opened fire on his convoy and killed him and another person."
A Misseriya official, Saddiq Babu Nimr, confirmed the death of Mayok but blamed it on a shooting incident with Ethiopian U.N. peacekeepers, which administer Abyei.
"A group of Misseriya asked his convoy travelling with 8 cars from the Ethiopians to stop to talk to them but the Ethiopians refused to do so," he said.
He added that one Ethiopian had then open fire and killed one Misseriya after he had readied his gun, triggering a shooting during which Mayok had been killed.
No more details were available, and the Ethiopian peacekeepers, the U.N.'s Interim Security Force for Abyei (UNISFA), could not be immediately reached for comment.
Abyei was meant to have like South Sudan an independence referendum but both sides have been unable to agree who should participate.
UNISFA has been running a temporary administration for Abyei since Sudan seized the region in May 2011 following an attack on an army convoy blamed by the U.N. on southern forces.
Sudan has withdrawn its forces since then from Abyei, which has fertile land and small oil reserves.
Relations between Sudan and South Sudan improved much in March with a deal to resume oil exports from the landlocked South through the north, throwing both a lifeline.
Juba had shut down its oil output in January 2012 after failing to agree with Khartoum on export fees. Both countries then came close to an all-out war when border skirmishes erupted in April 2012.
South Sudan is due to ship its first oil to export facilities in Sudan on May 10, Sudan's oil ministry told the state news agency SUNA on Saturday. (Reporting by Khalid Abdelaziz; Writing by Ulf Laessing; Editing by Eric Walsh)