Scottish aid agencies have launched an emergency appeal to help save lives in the Darfur region.
Militia groups have been accused of atrocities against civilians
About 4.5 million people have been affected by the conflict between Janjaweed militias and rebel groups in Darfur, in western Sudan.
About 200,000 people have died since fighting broke out in 2003.
The Disasters Emergency Committee said it feared the onset of the rainy season would increase the risk of deadly illnesses like diarrhoea and malaria.
The pro-government Janjaweed has been accused of atrocities including mass killings, rape and looting of black African villages in response to an armed uprising by local rebel groups opposed to the Sudanese authorities.
More than two million people have fled their homes to refugee camps elsewhere in Darfur and Chad.
The American government has accused both the Janjaweed and Sudanese authorities of committing genocide in Darfur.
The violence has spilled over the border into Chad, which has a similar ethnic make-up to Darfur, and the Central African Republic.
Aid agencies said funds were desperately needed to help provide shelter, clean water, sanitation and food to the millions of people caught up in the conflict.
Money is also required to enable more medical teams to provide emergency care in the region.
Anne McCulloch, a Scottish aid worker from Kilbirnie in Ayrshire, has just returned from Darfur, where she has worked as a child psychologist since 2004.
Ms McCulloch said: "The ongoing conflict continues to cause many difficulties for the women and children there.
"Their resilience is remarkable, but I know that even once the immediate crisis is over it will take a long time for these communities and especially their children to regain the confidence to return home and rebuild their shattered livelihoods. We need your support now."
CRISIS IN DARFUR
Two million forced to flee into camps
Four million dependent on humanitarian aid
232,000 refugees have fled into Chad
Rainy season can make access difficult
Gavin McLellan, chairman of the Disasters Emergency Committee in Scotland, said: "We are seeing one of the greatest concentrations of human suffering right now in Darfur and Chad and the impending rains will make the situation even worse.
"We have been keeping people alive but access is already severely hampered by conflict and the rains will make it much harder for us to respond if we don't act now."
BBC Scotland presenter Sally Magnusson will host an appeal film on Thursday evening as part of the appeal. Taggart actress Blythe Duff will present an appeal on STV.
Ms Magnusson said: "It is hard for most of us to imagine suffering on this scale - 4.5 million people have been brought to the brink of catastrophe.
"The increased violence has caused thousands of families to flee their homes, seeking safety in makeshift, overcrowded camps.
"Schools, shops and homes have been destroyed, some burned to the ground. Meanwhile others, who cling to life in their villages, are in constant fear of attack."
People can donate to the Darfur and Chad Crisis Appeal by calling 0870 60 60 900, at www.dec.org.uk or by visiting any post office, high street bank, Oxfam, Save the Children or Red Cross shop.
Donations can also be made by post. Cheques made payable to Darfur and Chad Crisis can be sent to DEC Darfur and Chad Crisis Appeal, PO BOX 999, London, EC3A 3AA.
The Scottish Catholic International Aid Fund (Sciaf) has also launched an appeal to raise funds for Darfur.
Donations can be made via its website or through an emergency donation line on 0800 027 9005.