More than 3,000 United Nations troops will be allowed into Darfur, according to Sudanese Foreign Minister Lam Akol.
The African Union force is struggling to halt the violence
The apparent change of heart comes after months of international pressure, but there is no UN confirmation so far.
Mr Akol told a news conference that Sudan has now fully accepted the second phase of a UN plan to support 7,000 struggling African Union troops there.
Under the plan, UN attack helicopters and armoured personnel carriers will also be deployed to help AU forces.
The four-year Darfur conflict between rebels and pro-government Arab militia has seen more than 200,000 deaths and at least 2.4 million displaced.
UN DARFUR PLAN
Phase 1 - UN financial backing for AU mission
Phase 2 - UN sends logistical and military support
Phase 3 - UN takes joint command of hybrid force
A spokesman for the foreign ministry told the BBC that Sudan's acceptance had been passed on to African Union Chairman Alpha Omar Konare.
Mr Konare is currently in New York to brief UN Secretary General Ban Ki-moon and the Security Council.
UN officials said they were aware of the Sudanese announcement, but had not yet been told anything officially.
Earlier, British aid agency Oxfam launched an appeal for humanitarian aid for the Darfur region of Sudan and east Chad.
Oxfam says it needs £5m ($10m) to help displaced people in the region who continue to flee from violence.
"This is the greatest concentration of human suffering in the world and an outrage that affronts the world's moral values," Penny Lawrence, Oxfam's international director said after a tour of Darfur.
The international aid agency is currently providing clean water, health and sanitation services to more than 500,000 people in Darfur and eastern Chad.
"Nearly 1 million people are not getting any aid at all and in some areas the aid efforts is under threat due to increasing insecurity," an Oxfam statement said.
Visiting US official John Negroponte had also warned Sudan of isolation if it fails to stop harassment of humanitarian workers and rejects the deployment of UN peacekeepers in the war-torn region.
"The denial of visas and harassment of aid workers has created the impression that the government of Sudan is engaged in a deliberate campaign of intimidation," he said at the end of his tour of Sudan.