African Union officials and aid agencies in the troubled Darfur region of Sudan say a controversial peace agreement signed in May has sparked a new round of fighting, which is threatening to shut down the world's largest aid operation.

Aid agencies say eight humanitarian workers in Darfur were murdered in July, making it the most dangerous month for humanitarian workers since the conflict began three years ago.

Half of the attacks took place in squatter camps sheltering 2.5 million refugees, who fled their homes to escape the violence unleashed after African tribes in Darfur took up arms against the Arab-led government in Khartoum.

To put down the rebellion, Khartoum recruited a mainly Arab militia known as Janjaweed, which the United States says committed acts of genocide against civilians in Darfur.

In May, Khartoum officials and the leader of the largest Darfur rebel group signed a power-sharing accord. But two other rebel factions rejected the deal, saying it did not go far enough to meet their basic demands.

Aid agencies report that the peace agreement has also raised sharp disagreements among refugees, who have taken out their anger and frustrations out on aid workers and underfunded African Union peacekeepers deployed to protect them.

A political analyst on Sudan, Mariam Juma, tells VOA that there is a clear need for a larger, more robust peacekeeping force to restore security to Darfur.

But Juma says she believes two factors - mainly the current war in the Middle East between Israel and Hezbollah and Sudanese President Omar al-Bashir's reluctance to allow U.N. forces to replace African Union troops in Darfur - are hampering international efforts to tackle Darfur's growing security problems.

"It is quite clear that there is support for an international force from the civil society component, mainly because they feel that the African Union's mandate has not been strong enough," said Juma. "The extent which current events in the Middle East are going to impact on peoples' perception of what the U.N. force can actually do remains to be seen. I think we must not forget that the Middle East has a significant impact on Sudan and the region and particularly on the ethno-religious dynamics of the country."

Last Monday, the Darfur rebel leader who signed the peace accord, Minni Minnawi, was named to the post of Special Assistant to President Bashir's ruling party. Juma says the move has created even more friction between Minnawi's Sudan Liberation Army and rival factions, who remain politically marginalized and fractured.

Since the peace deal was signed on May 5, at least two new breakaway factions have emerged to challenge Minnawi's Sudan Liberation Army rebel group. In the past two months, fresh clashes between the rebel factions have left scores dead and displaced nearly 50,000 more people.