Sudan has agreed to allow deployment of a joint United Nations-African Union peacekeeping force in its troubled Darfur region. VOA's Peter Heinlein at U.N. headquarters reports initial reaction to the news has been cautious.

A statement issued in the Ethiopian capital, Addis Ababa, Tuesday says Sudan has accepted a revised plan for a hybrid AU-U.N. peace mission in Darfur. The agreement was announced at the end of two days of talks involving all three parties.

AU officials say the force would be made up of between 17,000 and 19,000 troops, with an additional 3,700 police officers.

In New York, U.N. Secretary-General Ban Ki-moon hailed the agreement, in a statement read by spokeswoman Michele Montas.

"The secretary general welcomes today's positive conclusion of the high-level African Union-United Nations consultations with the government of Sudan on the hybrid operation and looks forward to expeditiously implementing the three-phase approach to peacekeeping in Darfur," she said.

The news from Addis Ababa raised immediate questions, and doubts among diplomats that the deal would hold up. One issue is the composition of the force.

U.N. peacekeeping officials see it as a mainly African force with an African commander, but under a broad United Nations command and control structure. But Sudan's president, Omar al-Bashir, has said he would insist that all the troops be African.

U.S. State Department spokesman Sean McCormack said a condition like that would be a deal-breaker.

"To say that the force will be limited to only African troops is in effect to say that you are not agreeing to the full 17,000 to 19,000 troops, which the experts believe is what you need to perform the mission," he said. "So it's a statement that on its face, would appear to accept everything. But in fact when you look at it, and examine it closely, it doesn't."

Several U.N. diplomats noted that Sudan's President al-Bashir has previously appeared to accept a blue-helmeted U.N. force when under pressure, only to back track later. They point out that the deal in Addis Ababa comes days before the Security Council is due to visit Khartoum to discuss deployment of the hybrid force.

Washington's U.N. Ambassador Zalmay Khalilzad says a number of Council ambassadors support increasing sanctions against Sudan unless it accepts the hybrid force arrangement.

"We have said if we don't get an unconditional acceptance of the AU-U.N. concept on the hybrid force, then several of us are of the view that we have to go with additional sanctions, tightening sanctions, to incentivize the government to cooperate," he said.

At the same time, Khalilzad said it is important to note that the violence in Darfur comes not only from the government and government-backed militias, but also from rebel forces. He said all sides have an obligation to comply with Security Council resolutions.

Darfur's civil war broke out in early 2003, when non-Arab rebels took up arms, charging the Sudanese government with ignoring their plight. Khartoum responded by arming Arab militias known as janjaweed to put down the uprising.

International experts say there have been more than 200,000 war-related deaths in Darfur since the fighting began. More than two million others have fled their homes to escape the violence.

Sudanese officials dispute those figures, saying only a few thousand people have died.