UN Secretary General Ban Ki-moon is visiting Sudan's western Darfur region, where a four-year conflict has claimed 200,000 lives and displaced millions.
UN Secretary General Ban Ki-moon has been met by protests during a visit to a refugee camp in Sudan's strife-torn western Darfur region.
Mr Ban is visiting a refugee camp. He is keen to try to finalise a date and venue for peace talks between the government of Sudan and rebel factions.
Mr Ban, in the area to help arrange a peacekeeping force, had to reschedule meetings after refugees confronted him, pleading for help to return home.
He has said the priority of his trip is to get a 26,000-strong UN and African Union peacekeeping force into position.
He said plans to send 26,000 troops from the UN and African Union, to arrive next year, were "on good track".
The new troops are not due to arrive until next year but violence continues.
At least 200,000 people have died more than 2m have been displaced since 2003.
The Khartoum administration and pro-government Arab militias are accused of war crimes against the black African population.
Correspondents say Mr Ban wanted to see for himself the plight of the people of Darfur and understand the difficult conditions into which the world's biggest peacekeeping force will eventually be deployed.
Complex situation
The camp near El Fasher in north Darfur state where he is going is said to be in a shocking condition.
The refugee camp Mr Ban visited, near El Fasher in North Darfur state, is said to be in an extremely poor condition.
The BBC's Laura Trevelyan, who is travelling with Mr Ban, says the visit is a delicate balancing act for Mr Ban, who has made Darfur his top priority.
Most of the refugees are black Africans - although reports suggested those who staged the demo were chanting pro-government slogans in Arabic.
He wants to encourage the Sudanese government, which has finally accepted peacekeepers, while condemning the killings and getting political talks going.
The BBC's Laura Trevelyan, travelling with Mr Ban, said the protests were an illustration of how complicated the Darfur situation is.
Mr Ban visited the south Sudan capital, Juba, on Tuesday to show support for the 2005 peace agreement that ended a 21-year civil war between the north and south.
Mr Ban was due to meet leaders of a number of groups living in refugee camps at El Fasher, but changed his arrangements after the protests.
Mr Ban called for both sides to live up to their commitmentsHe met Salva Kiir - the former rebel now Sudan's first vice-president under the deal.
Earlier, Mr Ban said it was now "crucially important" that Sudan's government holds talks with rebel factions.
Mr Ban said afterwards the peace agreement in southern Sudan was a blueprint for long-term peace in the country - including Darfur - but must be fully implemented.
He said the deployment of troops "should be accompanied by a political process, otherwise our peacekeepers or police or civilian workers will have a lot of difficulty in carrying out their roles".
Under the deal, the largely Christian and animist south is meant to be self-governing for six years, then it is to hold a referendum to decide whether or not to secede from Sudan.
Correspondents say Mr Ban decided to visit because he wanted to understand the difficult conditions into which the world's biggest peacekeeping force would eventually be deployed.
Our correspondent says preparations for the referendum are behind schedule and the border between north and south has not been drawn up, meaning the crucial agreement on how to divide Sudan's oil wealth evenly cannot be made either.
He also wants to encourage the Sudanese government, which has finally accepted peacekeepers, while condemning the killings and getting political talks going.
Mr Ban called for both sides to live up to their commitments.
Currently there are 10,000 UN peacekeepers in southern Sudan.
