Human Rights Watch has called for senior Sudanese officials - including the president - to be investigated for crimes against humanity in Darfur.
Millions of people have been displaced by the conflict
Its latest report names more than a dozen civilian and military officials it says helped co-ordinate militias and armed forces who attacked civilians.
Tens of thousands have been killed and two million displaced from their homes since the violence began in early 2003.
A Sudanese official dismissed the report as "ridiculous" and "baseless".
The BBC's Susannah Price in New York says the report reflects the frustration felt by many humanitarian workers, United Nations officials and diplomats about the lack of action taken against those involved in the violence in Darfur.
New York-based Human Rights Watch says the looting and destruction of villages in Sudan's western region was methodically organised, and that troops and Janjaweed militia members were allowed to take livestock and land.
It adds that the leadership in Khartoum relied on the civilian administration, the military and Janjaweed to implement a counter-insurgency policy that deliberately targeted civilians.
Human Rights Watch also says despite several Sudanese government initiatives, including a national inquiry, not a single mid- or high-level civilian official, military commander or militia leader has been held accountable.
Senior foreign ministry official Mutrif Siddiq told the BBC that the report was rebel propaganda.
Sudan's government has said that the violence in Darfur is a tribal conflict and the attacks are carried out by militias and rebels.
It denies that the state has co-ordinated the violence.
Earlier this year, a UN commission of inquiry concluded the crimes committed in Darfur might be no less serious than genocide and the Security Council subsequently referred the situation to the International Criminal Court.
The court's prosecutor, Luis Moreno Ocampo, will report on his progress to the council on Tuesday.