Kampala, Uganda -- The United Nations should impose penalties on top political and military leaders in Sudan and investigate crimes against humanity committed in Darfur, Human Rights Watch said in a report released Sunday. The report accuses officials from President Omar al-Bashir down of playing major roles in making civilians the target of attacks in Darfur.

The human rights group accuses many Sudanese officials of deliberately aiming attacks at civilians in Darfur, in western Sudan, as part of a counterinsurgency strategy that began after two rebel groups took up arms against the government in early 2003.

"Senior Sudanese officials -- including President Omar al-Bashir -- must be held accountable for the campaign of ethnic cleansing in Darfur," Peter Takirambudde, Africa director for Human Rights Watch, said in a statement.

The report was timed to coincide with a Security Council briefing today by Luis Moreno-Ocampo, the prosecutor of the International Criminal Court. The Security Council referred the atrocities in Darfur to the court in March with a sealed list of 51 suspects. In June, the court opened a formal investigation, which continues.

Sudan's government maintains that rebels regularly hid among villagers, imperiling civilians during military campaigns. The government has also sought to distance itself from the scorched-earth tactics of the Janjaweed militias, which have attacked civilians, despite evidence of coordination between military commanders and militia leaders.

Sudan's government has set up a national inquiry into the violence in Darfur, many committees to investigate accusations of rape by soldiers or militia members there and a national tribunal to try suspects. Yet Human Rights Watch said those actions had brought little improvement on the ground.