More than 60 people have been killed in Sudan's disputed region of Abyei over the past three days in a series of clashes involving local Dinka police force and militia allegedly associated with the nomadic tribe of Misseria, a senior official of the Abyei Referendum Forum (ARF) told Xinhua Monday.

The casualties included about 40 from Misseria and 24 Ngok Dinka civilians in the clashes from Friday and Sunday, ARF acting Chairman Deng Mading said. "We are getting more reports of casualties and the figures are being updated as the fights are going on."

The Dinka forces captured two tanks in the color of the United Nations peacekeepers from the enemies on Saturday and handed them over to the southern army Sudan People's Liberation Army (SPLA), he said. "We were checking the identity of the tanks."

The figure has not been confirmed by the United Nations. Reports over the cause of the violence are not clear with different reasons put forward by both sides.

The senior Misseria leader Hamdi al-Doudo was reported by Sudan Tribune as saying that the clashes were triggered by the SPLA moving up to 1,500 soldiers into the area, which the Arab nomads regarded as a route to grazing fields.

But Mading said the alleged reasons are "absolutely not right."

"Actually, the invading forces are moving 3,000 troops to Abyei, " he told Xinhua.

People in the oil-producing Abyei were promised a referendum on Jan. 9 on whether to join the north or south, but the plebiscite was postponed due to a dispute over whether the Misseria, who enter Abyei for a few months each year to graze cattle, should be given the right to vote.

Sudan's ruling National Congress Party (NCP) has demanded the Misseria be allowed to vote, while the Sudan People's Liberation Movement which governs the south says that only the Dinka Ngok have the right to participate, thus leaving a thorny task to settle the region's future status through negotiations.

"Just as commitments were made for a southern Sudan referendum, so were binding commitments made for an Abyei referendum. We must have resolution of our status," Mading said.

"There is still time for Abyei," Mading said, "We call upon President Bashir and President Kiir to sit together and recommit themselves to the final resolution of Abyei which is provided for in the CPA."