KHARTOUM (Reuters) - Efforts to implement a peace deal between Sudan's government and a Darfur rebel group face "huge challenges" while violence is rising in parts of the western region, the acting head of the regional peacekeeping force said on Monday.

Insurgents took up arms against government forces in Darfur in 2003, complaining authorities had neglected the region and excluded their ethnic minorities from economic and political power structures.

Despite a massive United Nations-African Union peacekeeping force (UNAMID) deployed in Darfur, rebel fighting, banditry and tribal clashes have continued to plague the territory.

In July last year the government signed a Qatar-brokered peace deal with the Liberation and Justice Movement (LJM), an umbrella group of small rebel factions, but the main insurgent groups refused to sign.

Implementing the deal has been slow since then, acting UNAMID head Aichatou 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, can even be described as stagnant," she told reporters in Khartoum.

A process to verify the LJM forces and strength was conducted in March but has not produced conclusive outcomes, she said, adding that the deadlock meant there had been no progress on major provisions of the deal.

She added that a regional conference authorities had been able to hold was one sign of progress.

"While the overall process of DDPD (Document for Peace in Darfur) implementation has been very slow and continues to face huge challenges, some progress has been made," she said.

The United Nations has estimated that around 300,000 people may have died in the Darfur conflict. The government has put the toll around 10,000.

The International Criminal Court has indicted Sudan's President Omar Hassan al-Bashir for masterminding war crimes and genocide in the region, which he denies.

A spike in clashes between groups in northern Darfur has led to high civilian casualties recently, Mindaoudou said.

"This alarming development calls for urgent and speedy implementation of this plan," she added.

(Reporting by Alexander Dziadosz; Editing by Jon Hemming)