Rights group Amnesty International on Thursday accused Sudanese government forces of killing scores of civilians, including many children, in suspected chemical weapons attacks in a mountainous area of war-torn Darfur.
More than 30 such attacks are believed to have been carried out on several villages as part of a massive military campaign against rebels in Darfur's Jebel Marra between January and September, Amnesty said in a report.
The group said its investigation "has gathered horrific evidence of the repeated use of what are believed to be chemical weapons against civilians, including very young children, by Sudanese government forces in one of the most remote regions of Darfur over the past eight months".
"Between 200 and 250 people may have died as a result of exposure to the chemical weapons agents, with many or most being children," the report said.
Amnesty said government forces also carried out "indiscriminate bombing of civilians... unlawful killing of men, women and children and the abduction and rape of women" in Jebel Marra, home to Darfur's most fertile land.
The nearly 100-page report contains gruesome photographs of children suffering from apparent chemical burns, satellite images of destroyed villages and displaced people, interviews with more than 200 survivors, and analysis by chemical weapons experts.
Amnesty said the attacks were part of a military operation against the rebel Sudan Liberation Army - Abdul Wahid (SLA/AW) group, which Khartoum accuses of ambushing military convoys and attacking civilians.
Sudan's military rejected the allegations.
"Amnesty's report is incorrect because the situation on the ground does not need intensive bombing as there is no real presence of rebels anymore," army spokesman Brigadier Ahmed Khalifa a-Shami told AFP.
"There is also a clear order to our troops not to target rebels if they happen to be in villages or in areas inhabited by civilians."
Amnesty's crisis research director Tirana Hassan said tens of thousands of people had been driven from their homes since the air and ground campaign began in January in Jebel Marra -- the homeland of the ethnic Fur tribe.
"The evidence we have gathered is credible and portrays a regime that is intent on directing attacks against the civilian population in Darfur without any fear of international retribution," she said in a statement.
Amnesty said the attacks amount to "war crimes" and "crimes against humanity".
Sudan, which was slapped with US trade sanctions in 1997, is a signatory to the Chemical Weapons Convention.
Darfur has been engulfed in a deadly conflict since 2003 when ethnic minority groups took up arms against President Omar al-Bashir's Arab-dominated government, which launched a brutal counter-insurgency.
At least 300,000 people have been killed and 2.5 million displaced, the United Nations says.
Bashir is wanted by the International Criminal Court on war crimes and genocide charges related to Darfur, which he denies.
In recent months Sudan has insisted that the conflict in Darfur has ended, and it wants UN peacekeepers who have been deployed in the region the size of France since 2007 to leave.
Amnesty said there was "credible evidence" that at least 32 villages in Jebel Marra were attacked with bombs and rockets containing chemicals.
"Many photos show young children covered in lesions and blisters. Some were unable to breath and vomiting blood," Hassan said.
She added that there had been "horrific burns and skin reactions to the agents... and some of the first responders and caregivers have told us that even when they touch the skin, it actually falls off in large chunks."
The rights group said experts had concluded the victims were exposed to vesicants, or blister agents, such as sulfur mustard, lewisite or nitrogen mustard.
"When (the bomb) fell there were some flames and then dark smoke," a woman who survived an attack with her baby was quoted as saying in the report.
She said the bombing had caused vomiting, dizziness, skin problems and headaches.
"The baby is not recovering... he is swollen... he has blisters and wounds."
Amnesty urged Sudan to allow humanitarian workers and UN forces immediate access to Jebel Marra.
Darfur "has been stuck in a catastrophic cycle of violence for more than 13 years. Nothing has changed except that the world has stopped watching," Hassan said.