Javier Solana, the EU foreign policy chief, said on Thursday that he could not guarantee the African Union would come to an agreement about a UN mission on Friday, despite two days of inconclusive efforts to persuade Ali Osman Mohamed Taha, the Sudanese vice-president.
Taha said from Brussels that Khartoum could consider an unspecified UN role if talks with separatists being held in the Nigerian capital yielded a deal to resolve the conflict.
"If there is a political settlement then by way of providing guarantees to make the settlement hold, then we can look into the role of the UN there and then," Taha said on Wednesday.
But Solana said that could be too late.
"That goes a little bit too far, because that means he only will accept after the Abuja talks have given a result, but we cannot risk not to start with the planning if necessary in case the Abuja talks take longer," Solana said.
Opposition politicians in Sudan denounced the government's media campaign as misleading and cast doubt on the spontaneity of a protest march in the capital on Wednesday.
The opposition says the government's knee-jerk reaction is being driven by the military, which fears UN forces in Darfur might be asked to arrest those accused of alleged war crimes by the UN's International Criminal Court (ICC).
Two million Sudanese have been
displaced in the Darfur region
The US has condemned the violence in Darfur as genocide and accuses Sudan's Khartoum-based government of fighting mostly non-Arab separatist movements in Darfur by arming Arab militias known colloquially as the Janjaweed.
Khartoum denies genocide and says it armed some tribes but denies links to the Janjaweed.
The Janjaweed have carried on a campaign of rape and pillage across the western Darfur region, terrorising villagers, destroying crops and burning down homes in a three-year conflict that has left two million people homeless.
Mubarak al-Fadil al-Mahdi, head of a breakaway faction of the Umma Party, said a strong UN force could police the region and bring an end to Darfur violence.
"You need to bring a formidable force to protect the people in Darfur," he said. "The UN ... would have a better chance of doing that."
In a related development, the police arrested two journalists after they published a story that reported on an offer to pay for the assassination of a top UN envoy, an employee of their newspaper said on Thursday.
The independent Al-Watan paper this week quoted the head of the pro-government students' union, Mohamed Abdallah Sheikh Idriss, as saying the body would pay $100,000 for the head of UN envoy to Sudan, Jan Pronk.
"The editor-in-chief (Sid Ahmed Khalifa) was arrested yesterday," said Khaled Sati, managing editor of Al-Watan. He added the authorities had accused Khalifa and the journalist who wrote the article, Mustafa Abu al-Azaim, of incitement.
A spokesman for the student's union denied Idriss had offered a ransom for Pronk's head.