Salva Kiir Mayardit, one of Sudan's two vice-presidents and head of the Sudan People's Liberation Movement (SPLM), said in remarks published on Saturday by the daily Al-Sudani that the Sudanese government was incapable of protecting civilians in Darfur, and called on the United Nations to intervene.
"The aggravation of the humanitarian and security situation in Darfur necessitates intervention of international forces to protect civilians from the atrocities of the Janjawid militias so long as the government is not capable of protecting them," he said at the close of an SPLM politburo meeting held in the southern city of Juba late on Friday.
Kiir's rebel group signed a peace agreement with the Sudanese government in January 2005, laying down its arms after 21 years of civil war - Africa's longest.
Kiir participated in talks in Abuja, Nigeria, that led to the signing the Darfur Peace Agreement in May. His organisation is believed to have influence over the Darfur rebels, although the conflicts were not related.
In June, George Bush, the US president, had pressed Kiir to accept a UN force in Darfur, but Kiir sidestepped the issue, saying only that "we are sure that we are going to solve the problem so that we don't hear about rapes and killings in Darfur".
The newspaper on Saturday also quoted Bagan Amom, the SPLM secretary-general, as calling on the National Congress Party of Omar al-Bashir, the president, to "accept deployment of UN forces in Darfur to avert clashes with the international community".
Amom said the SPLM would "work at convincing the National Congress to agree to the deployment of UN forces in Darfur".
Tony Blair, the British prime minister, said earlier on Saturday that he would propose an incentive package for Sudan as part of a new initiative to end the crisis in Darfur and get UN peacekeeping troops on the ground.
"In the coming weeks I will talk to other leaders to agree an initiative that sets out the help Sudan can expect if the government lives up to its obligations and what will happen if they don't," Blair said.
The western region of Sudan bordering Chad has been plagued by political and ethnic violence since 2003.
Tens of thousands of people have been killed and more than two million displaced by fighting between government troops, rebels and militias.