A UN team will travel later this week to Sudan's Darfur region where a surge in fighting has sent civilians fleeing, the UN spokesman said Thursday.
The mission will travel to Tawila in North Darfur but Khartoum has denied a request for the team to visit affected areas in central Darfur due to the ongoing fighting, said UN spokesman Stephane Dujarric.
UN aid agencies are receiving reports of "significant civilian displacement" and of "direct attacks on civilian villages" in the area of Jebel Marra, said Dujarric.
The United Nations called on all sides to allow access for humanitarian aid in Darfur, where fighting since 2003 has displaced two million people.
The Sudanese army last week said its troops had driven out insurgents from the Fanga area of Jebel Marra, but the rebels denied the claim.
Last month Sudan's military announced operation "Decisive Summer 2" to crush insurgents in Darfur and the Blue Nile and South Kordofan regions.
It was dubbed a "summer" campaign because it was launched after the end of Sudan's rainy season, which lasts from July until November and renders roads impassable.
Ethnic insurgents in Darfur rebelled against the Arab-dominated government in Khartoum in 2003, complaining of discrimination against them.
The conflict has killed 300,000 people, the UN says, although the government puts the death toll at 10,000.