Sudan ended Africa's longest running civil war with a 2005 peace deal but north and south were unable to agree on the future of Abyei, which many fear will become Sudan's "Kashmir", a problem that could reignite conflict if left unresolved.
Abyei residents are set to vote on January 09 in a plebiscite to be held simultaneously with a referendum on southern independence, which analysts believe will result in secession.
The north says the Arab nomadic Missiriya, who spend months each year grazing cattle in Abyei, should vote in the plebiscite but the south disagrees. The resulting deadlock has stalled planning and the two have yet to agree on a commission to organise the vote due in almost three months.
"If they don't accept our votes in the referendum there will be no voting," the head of the Missiriya, Mokhtar Babo Nimr, told Reuters on Wednesday.
"We will use force to achieve our rights and we will use weapons against anyone who tries to stop us from voting in the referendum," he warned.
The Hague-based Permanent Court of Arbitration ruled on Abyei's borders after the north-south former foes could not agree. But the frontier has not been demarcated on the ground because of threats from the Missiriya who reject the ruling.
List of demands
Eye witnesses said about 2 000 Missiriya demonstrated in the central town of Muglad on Wednesday and handed a list of demands to the UN office there including reviewing Abyei's borders and their right to vote in the plebiscite.
"If they don't meet our demands then we will set everything alight," said Babo Nimr. "If that leads to war then so be it."
Analysts believe unresolved disputes between local communities such as the Missiriya could flare up and drag the north and south back into the devastating civil war which claimed two million lives and destabilised much of east Africa.
The cattle-herding Missiriya fear if the south secedes and the north-south border becomes an international boundary, they will lose grazing rights to the land and their livelihoods.
The tribe is heavily armed and some tribesmen were recruited by the northern government to fight the south as a proxy militia during the north-south conflict.
Abyei is on the Muglad basin which produces Sudan's most valuable Nile Blend crude but further exploration has been hindered by insecurity in the area.