Machel said the Sudanese government had to accept the fact that there was rape and then help form a plan to combat it.
The group also called for the speedy deployment of the 26,000-strong UN-AU force in Darfur.
Meanwhile, Reuters reports quoting the Ethiopian prime minister that the country will contribute 5,000 troops to the hybrid force.
Meles Zenawi said in Addis Ababa on Thursday: "Ethiopia is ready, the troops are equipped, and we are waiting for a request from the AU and the United Nations to disperse the troops to Darfur."
Jimmy Carter said Khartoum should hand over to the ICC a junior government minister and militia leader wanted for war crimes.
"Genocide is a crime against humanity as a whole, not just against it's immediate targets. It therefore falls on the world at large to act."
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He said it was unacceptable that Khartoum had appointed Ahmed Haroun, state minister for humanitarian affairs, as head of a rights committee.
But Carter also criticised the US use of the term genocide to describe the situation in Darfur, where international estimates say 200,000 people have died and 2.5 million driven from their homes, as unhelpful.
"There is a legal definition of genocide and Darfur does not meet that legal standard. The atrocities were horrible but I don't think it qualifies to be called genocide," he said.
Washington is almost alone in branding the four and a half years of violence in Darfur "genocide".
Khartoum rejects the term, European governments are reluctant to use it, and a UN-appointed commission of inquiry found no genocide, but that some individuals may have acted with genocidal intent.
During their visit, which began on Sunday, The Elders met Omar al-Bashir, the Sudanese president, and held talks with members of the semi-autonomous government in Juba, capital of south Sudan.
Thr Sudanese authorities say only 9,000 people have died in the conflict.
A peace deal was signed between Khartoum and one of three negotiating rebel factions in May 2006 but violence has continued.
It is hoped that peace talks in the Libya on October 27 between all the Darfur rebel groups and the Sudanese government might help to bring a definitive end to the violence.