KHARTOUM: Parts of Sudan's Darfur region have seen an alarming rise in violence with high civilian casualties, the acting head of Darfur's peacekeeping mission said on Monday, as efforts to implement a peace deal between the government and some rebels hit deadlock.

"We are witnessing an increasing number of security-related incidents in North Darfur, including armed clashes between members of different communities with high civilian casualties," Aichatou Mindaoudou said.

She was speaking at the opening of the second meeting of the international Joint Commission, set up under a peace deal between the government and an alliance of rebel splinter factions, the Liberation and Justice Movement (LJM).

She called the trend in violence in the vast western region an "alarming development".

Mindaoudou did not refer to specific incidents but the African Union-United Nations Mission in Darfur (UNAMID) on Sunday said it plans further "assessment" of reported violence in North Darfur state's Hashaba.

The United States says 70 civilians died there between September 25 and 27 in fighting and aerial bombardments between rebels and Sudanese government forces.

Hashaba is in Kutum district, which has been the scene of unrest since early August when a district chief was shot dead during a carjacking attempt.

That attack sparked retaliatory violence that left several people dead and forced 25,000 to flee from a camp for those already displaced by fighting in Darfur's nine-year-old conflict.

In early September, authorities imposed a curfew and placed two districts under military rule after another attack targeting the top official in Kutum town.

Further west, four Nigerian peacekeepers were killed on October 2 in an ambush near El-Geneina, in West Darfur state.

The Joint Commission membership includes the LJM, the government, UNAMID, Qatar, the European Union and the Arab League. Canada, China and Norway are observers.

The body is tasked under the July 2011 Doha peace deal with overseeing arms control through the safe storage of the LJM's heavy weapons, the integration of its fighters into Sudan's armed forces, and other measures under a ceasefire.

Mindaoudou said "no progress" had been made towards these goals because the first step, the verification of the LJM's forces and strength, had been "inconclusive."

"It is evident that the impasse in the verification exercise will significantly impede the establishment of a secure environment, a prerequisite not just for the voluntary and dignified return of IDPs (internally displaced persons) and refugees, but also for the effective and evenly spread implementation of reconstruction and development projects," she said.

A report in July by The Small Arms Survey, a Swiss-based independent research project, cited government figures of the LJM's strength as no more than 1,000-2,000 combatants.

Darfur's key rebel groups rejected the Doha deal but at the Joint Commission's first meeting last December there was optimism that the agreement with the LJM would be fully implemented, Mindaoudou said.

"Today, we have to note that the process has been very slow and, in the case of the work of the Ceasefire Commission, the process can even be described as stagnant," she said.

The LJM representative at Monday's meeting, Abul Abbas Abdullah Altayyeb, said verification of his movement's forces had been completed in some areas but not in others.

He and the government delegate, Osman Dirar, both said they are committed to implementing the security arrangements.

Much of the unrest in Darfur now is linked to pro-government Arab groups, which fight among themselves as well as against the regime, because "they feel protected," humanitarian sources have previously said.

Ethnic minority rebels rose against the Arab-dominated Khartoum government in 2003. In response, the government unleashed state-backed Janjaweed Arab militia in a conflict that shocked the world and led to allegations of genocide.

The UN estimates that at least 300,000 people died but the government puts the toll at 10,000.

Although violence is down from its peak, clashes between key rebel groups and government troops, banditry such as carjackings, and inter-ethnic fighting continue.