Gunmen on horseback attacked a truck carrying medicine and aid in Sudan's war-ravaged Darfur region and killed around 30 civilians on board, some of whom were burned alive, the United Nations said on Sunday.
The African Union had earlier put the death toll at 22 and said 10 others were wounded on Saturday when gunmen attacked the vehicle near Sirba, 45 km (30 miles) north of El Geneina, capital of West Darfur state and close to the Sudan-Chad border.
"The gunmen were riding on horseback. The exact number of civilian casualties is not yet established but it is estimated that around 30 people were killed," UN spokeswoman in Sudan Radhia Achouri said on Sunday.
"Some people were shot, others were burned to death," she said. The vehicle was carrying medicine and relief items and transporting people, Achouri added.
The violence highlights the worsening situation in Darfur where experts say around 200,000 people have been killed since the conflict flared in 2003 when rebels took up arms against the government, accusing it of neglect.
A May peace deal between the government and one faction of the Sudan Liberation Movement (SLM) has failed to stop Darfur bloodshed.
Analysts say all sides of the conflict - rebels, government forces and Arab militias allied to the government - are engaged in fresh fighting. Some aid workers say the humanitarian situation has not been as bad since 2003.
Achouri did not identify precisely who was behind Saturday's attack. Militias locally known as the Janjaweed, which the Khartoum government is accused of backing, are known to carry out some attacks in the region riding camels and horses.
In November suspected Janjaweed attacked Sirba, killing up to 30 villagers and wounding 40.
Khartoum denies supporting the Janjaweed, a term loosely derived from Arabic for "devils on horseback".
Mohamed al-Tulib, the acting governor of West Darfur, said Saturday's attack was carried out by the National Redemption Front (NRF) rebel group, the official Sudanese news agency (SUNA) quoted him as saying.
There was no comment from the NRF, a coalition of rebel groups that rejected the May peace deal.
AU APPEAL:
The African Union, which had dispatched an investigation unit to Sirba, said its team was able to leave the area after angry villagers initially prevented them from departing.
"We appeal to everybody to know that the AU is in Darfur to help the people and restore stability and reach peace. We are not in Darfur to be part of the conflict," AU spokesman in Sudan Noureddine Mezni said.
The African Union, which maintains an under-funded and overstretched force of 7,000 in Darfur has been unable to stop the violence in the vast region.
Janjaweed gunmen killed two civilians in El Fasher, Darfur's main town, on Saturday, witnesses and former rebels said.
The Sudanese government has repeatedly rejected a UN Security Council resolution authorising the deployment of 22,500 UN troops and police to Darfur, saying they would amount to a colonising force.
Sudan has accepted UN logistical and financial support for an expanded African force but wants a voice in deciding how many troops can be on the ground, which could be difficult to sell to the UN Security Council.
US envoy for Sudan Andrew Natsios arrived in Khartoum on Saturday to discuss Darfur with the government. He is scheduled to visit the region later this week.