Beshir and 15 other current and former senior officials in the Khartoum government, military commanders and local administrators should be subjected to UN sanctions and probed for war crimes and crimes against humanity in Darfur, Human Rights Watch (HRW) said on Monday.
"The Sudanese government at the highest levels is responsible for widespread and systematic abuses in Darfur," HRW said in a report entitled "Entrenching Impunity: Government Responsibility for International Crimes in Darfur."
"Senior Sudanese officials ... must be held accountable for the campaign of ethnic cleansing in Darfur," said HRW's Africa director Peter Takirambudde.
The New York-based group called for the UN Security Council and individual nations to take stronger measures to atrocities there and boost the African Union (AU) military mission in the region.
And it called on the International Criminal Court (ICC), the world's first permanent war crimes tribunal, to investigate Sudan's entire leadership for possible prosecution for the abuses.
It named Beshir, Sudan's Second Vice President Ali Osman Taha, Defense Minister Abduraheem Hussein, armed forces chief of staff Abbas Arabi and intelligence chief Salah Abdallah Ghosh as among those suspect of orchestrating repression in Darfur.
They "should be investigated for crimes against humanity and war crimes, either as a matter of individual criminal responsibility or command responsibility," HRW said in the nearly 90-page report.
War broke out in Darfur in 2003 when rebel groups began fighting what they say is the political and economic marginalisation of the region's black African tribes by the Arab-led regime in Khartoum.
As many as 300,000 people have died and more than two million fled their homes in what UN aid agencies have dubbed the world's worst humanitarian crisis with reports of rapes, extrajudicial killings and other atrocities rampant.
Much of the abuse is blamed on Khartoum's proxy militias -- the so-called "Janjaweed" -- but in its report, HRW placed responsibility higher, citing witness accounts from refugees and interviews with Sudanese soldiers and officials.
Based on those accounts, HRW said: "the looting and destruction of villages was not just condoned by government officials, it was methodically organized, with troops and militia members permitted to take land, livestock and other civilian property."
Although the Sudanese army itself appears to have ended operations in Darfur, the Janjaweed are still active and despite promises to rein them in, Khartoum has done little to end the abuses of its proxies, it said.
"The Sudanese leadership continues to implement policies that permit continuing attacks on civilians and perpetuate a climate of fear and intimidation through structural and institutional abuse," HRW said.
"(It) has shown no sign that it is prepared to fundamentally change its policies," the report said.
"If the ongoing abuses in Darfur are to be stopped, and if the ethnic cleansing is to be reversed, then the UN Security Council, regional bodies and other governments must sharply increase their sanctions on the Sudanese government for human rights crimes," it said.