Sudan's deputy foreign affairs minister, Najib Abd al-Wahab, told journalists on Wednesday that the current draft document "contradicts obligations that we have already undertaken".
"For example, this protocol speaks about reduction of forces while we have already taken a commitment to the UN to deploy police forces in Darfur so that law and order can prevail," he said.
"We want an adjournment to enable us to properly study the draft and forward our observations to the mediators," Abd al-Wahab said, adding that the draft protocol in its current form is unacceptable to Khartoum.
But a spokesman for the rebel Sudan Liberation Movement (SLM) negotiating team said Khartoum's demands are proof that it is not sincerely committed to working for peace in Darfur.
Commending the AU protocol, SLM spokesman Abd al-Hafidh Musa said if any criticism was due, it was that the protocol did not go far enough.
He noted that it needed to include other issues, such as the withdrawal of government troops from Darfur and checks on the so-called Janjawid militias.
"The issue of an independent international body to probe the atrocities in Darfur and bring the perpetrators to justice should also be looked into," he added.
"This protocol speaks about reduction of forces while we have already taken a commitment to the UN to deploy police forces in Darfur so
that law and order
Najib Abd al-Wahab,
Sudanese Deputy Foreign Affairs Minister
"Our main concern is the deplorable humanitarian crisis in Darfur. The enabling environment should be created for the people to return home and for the aid agencies to have access to the affected areas," he added.
Nigeria's President Olusegun Obasanjo, who is AU chairman, is "very likely" to meet the two opposing sides on Thursday afternoon as part of his efforts to advance the peace talks, an AU official said.
The Abuja talks began on 23 August and are aimed at resolving the Darfur crisis, which has killed an estimated 50,000 people and forced another 1.4 million to flee their homes. But in three weeks, the talks have made little headway.
Last week, the talks were deadlocked over how to solve the humanitarian problem in the crisis-ravaged Darfur region. An accord on the issue was finally struck last Wednesday following pressure from the AU and Nigerian mediators.