There was no immediate comment from South Sudanese authorities, and a spokesman for the ruling military in Sudan did not answer a request for comment.
The deployment followed renewed fighting within and around Abyei, said the mission, known as UNISFA. It urged both parties to stop fighting and “allow the political process to resolve the lingering crisis.”
“UNISFA is against any form of unauthorized deployment” in Abyei, the mission said.
The mission statement did not elaborate on the fighting. Local media, however, reported that the latest clashes between Nuer and Dinka Ngok tribes in the region grew out of cattle rustling late last month. Citing local authorities, Sudan Tribune news website said at least 18 people were killed and nine were wounded.
UNISFA said it has reinforced peacekeepers in the area and “is closely monitoring the situation.”
The dispute between Sudan and South Sudan over oil-rich Abyei began when South Sudan gained independence from Sudan following a 2005 peace deal, after decades of civil war between Sudan’s north and south.
The deal called for both sides to settle the final status of Abyei through negotiations, but it is still unresolved. U.N. peacekeepers were deployed to the region in 2011, the year South Sudan became an independent country.