The United Nations has begun supplying emergency aid to the victims of fighting in a western Sudan region.
Thousands of displaced people are in need of relief supplies
The United Nations refugee agency is mounting an emergency airlift in eastern Chad to bring supplies to more than 100,000 Sudanese refugees.
The operation coincides with a UN World Food Programme airlift of supplies into northern Darfur, which has been cut off by the conflict since November.
A rebellion began a year ago after complaints of neglect by Khartoum.
The refugees, who have fled fighting in Darfur, are stranded in a remote area on the border between Chad and Sudan .
The UNHCR airlift of supplies coincides with an operation by the agency to move the refugees to camps further inland.
An agency spokesman said it was urgent that the refugees be moved to safety.
"We still have a long way to go in this race against time
and the elements," the UNHCR's Ron Redmond told a news briefing.
Last week, the Sudanese Government announced it had regained full control of the Darfur region, but rebels from the Justice and Equality Movement (Jem) and Sudan Liberation Army (SLA) insist they control much of the countryside and on Monday said they had launched a new front.
Also on Monday, students from Darfur staged a protest in the capital, Khartoum, to call for the UN to investigate the humanitarian crisis in the war-torn region.
In a statement they delivered to the UN office in the city, they accused government forces of carrying out mass killings, ethnic cleansing and arbitrary arrests.
The UN's Dr Mukesh Kapila told the BBC that it was still too dangerous for aid to be taken into Darfur by road, despite the Government opening humanitarian corridors last week for access.
Aid agencies estimate that the fighting has cut off some three million people for several months.
Dr Kapila appealed for more international help to fly in emergency relief supplies.