Beshir has promised to cooperate with US

The US envoy is in Khartoum on a four-day visit, his first since being appointed to the post by President George W Bush in September.

Sudan's official news agency reported that Mr Danforth is also expected to meet leaders of the rebel Sudan People's Liberation Army and human rights groups.

Terrorism

The US extended sanctions against Khartoum earlier this month, saying it had concerns about Sudan's involvement in terrorism and human rights violations.

Sudan had welcomed the appointment of Mr Danforth but said that cooperation with him depended on "an impartial and unbiased policy by the American administration."

Sudan has frequently accused Washington of siding with the rebels.

Mr Bush has called the conflict, between the Muslim government in Khartoum and the mainly Christian rebels in the south, in which some 2m people have died, "brutal and shameful".

The rebels are fighting for autonomy.

Peace within

At least four previous US attempts to end the fighting have failed and at the time of his appointment Mr Danforth said: "The possibility of peace depends on the will of combatants not on the intentions of outsiders."

Sudan has accused America of siding with southern rebels

President Bush was forced to act on Sudan following pressure from the left, concerned about continued slavery and right-wing Christians worried about reports that Christians were being persecuted by the Muslim government.

The recent discovery of oil has added a new element to the Sudan conflict.