The UN high commissioner for refugees says Sudan's government should grant more autonomy to the Darfur region in a bid to end continuing violence there.
Sudan is threatened with sanctions if it does not protect civilians
Ruud Lubbers told the BBC his idea might be controversial, but he said it was in his nature to speak his mind.
His idea of a loose, federal political system in Sudan is something rebels in Darfur have been advocating for years.
More than a million Darfur residents have fled their homes, and thousands are said to be dying every month.
Mr Lubbers begins a visit to Chad and Sudan on Friday to raise awareness of what UN officials describe as the worst humanitarian crisis in the world.
"My gut feeling is the best would be that Sudan finds itself in a way where it accepts relative autonomies of regions," he said.
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"Now it's a bit controversial maybe as a High Commissioner - but I have learned through the years just to speak my mind," he added.
The BBC's Mark Doyle, travelling with Mr Lubbers, says it is unusual for UN officials to enter the political arena in this way.
However, Sudan ambassador to London, Hassan Abdin, told the BBC that he saw nothing wrong with what Mr Lubbers had said, as the question was already being negotiated.
Earlier this year, the government agreed a deal with a separate rebel in the south, giving them autonomy and a share of the region's oil-wealth.
Aid workers say that refugees continue to flee new attacks in Darfur, despite the presence of thousands of extra police officers in the region, sent by the government under strong pressure from the international community, which has threatened to impose sanctions.
"Last week, there were 20,000 people who had fled attacks in Nyala, in South Darfur," Bastian Vigneau operations director for Medecins Sans Frontieres, told the BBC.
The Sudan government blames the refugee crisis on the rebels who started an insurgency in Darfur last year, accusing the authorities of ignoring the region.
On Wednesday, the rebels attacked targets outside Darfur for the first time, the government said.
But the UN says this relatively small rebellion was then countered with a scorched earth policy by pro-government Arab militias which led to black Africans to flee their homes.
The US has described the Janjaweed militia attacks as genocide and accuses the government of backing them - a charge rejected by Sudan.
Some Arab countries and China have been less critical, saying Sudan has a right to defend its sovereignty against the rebels.
The African Union has pledged to send up to 5,000 troops to protect civilians but says it needs some $200m to pay for it.
Canada has pledged $16m and the US Senate has approved $75m - but this amount still needs to be passed by the House of Representatives and President George W Bush.
While the Sudan government has promised to comply with the UN resolution threatening sanctions unless the pro-government militias are disarmed, officials say this does not mean disarming all of Darfur's Arabs, as some in the international community think.
The government blames the violence on rebel groups
"The government and international community are not in agreement over the definition of the Janjaweed," ruling National Congress party Secretary General Ibrahim Omar said.
"We do not consider Arab tribes and their leaders Janjaweed," he said.
The refugees have also said that some militiamen have now joined the police - and are guarding the refugee camps.