The results of an unofficial referendum show that 99.9 percent of the voters in disputed Abyei, mostly from Ngok Dinka tribe, have voted to join South Sudan.

Luka Biong, the spokesman for the Abyei Referendum High Committee, said on Thursday that the official results indicated that the number of people “who have chosen to become part of South Sudan is 99.9 percent of the vote.”

Tim Flatman, an independent observer in Abyei, said that 63,433 of the 64,775 registered voters participated in the referendum.

People in Abyei went to the 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.

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

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 mainly home to the two tribes of Ngok Dinka and Misseriya. Members of Misseriya, however, did not take part in the referendum.