The feuding Misseriya tribe and Ngok Dinka tibe of the disputed Sudan district of Abyei on Monday both reported heavy losses in clashes over the past three days with figures citing at least 33 dead.
"Thirteen Misseriya have been killed and 38 wounded since Friday," Misseriya tribal leader Hamid Al-Ansari said.
Abyei chief administrator Deng Arop Kuol said: “Over the past three days, we have lost about 20 to 22 Dinka. They attacked us three times already and we are expecting them to attack again today.”
Tensions in the district on the north-south border have been rising with the launch of a landmark independence referendum in the south on Sunday.
Abyei had been due to hold a simultaneous plebiscite on its own future but it has been indefinitely postponed.