Vote counting is underway in Abyei after residents of the contested African region took part in an unofficial referendum to decide whether they belong to Sudan or South Sudan.

People in Abyei, mostly from Ngok Dinka tribe, went to polls on October 27 in a three-day long referendum, which closed on Tuesday.

The referendum had been organized by a civic group. It lacked the official backing of the governments of Sudan and South Sudan.

Organizers believe that the majority of 65,000 registered voters have cast their ballots in the referendum.

The poll was held despite a warning by the African Union that the event is “a threat to peace” in the region.

Nkosazana Dlamini-Zuma, an African Union official, stated on Wednesday that the organizers of the referendum “pose a threat to peace in the Abyei area, and have the potential to trigger an unprecedented escalation on the ground... with far-reaching consequences for the region as a whole.”

The referendum is expected to inflame tensions as Khartoum and Juba both claim sovereignty over the oil-rich region.

The status of Abyei remained unresolved after South Sudan became independent from its northern neighbor in 2011.

The area is home to two main tribes of Ngok Dinka and Misseriya.

Members of Misseriya did not take part in the referendum.

Recently, Sudanese President Omar al-Bashir held talks with his southern counterpart Salva Kiir to settle the dispute over the future of Abyei, but the meeting ended inconclusively.