"It is time to break the silence," he said.
Moreno-Ocampo said Harun, who is suspected of involvement in the murder, rape, torture and persecution of civilians in Darfur, is now in charge of the millions of people he forced out of villages into camps.
"Ahmed Harun is not protecting the camps, he is controlling them. He must be stopped. He must be arrested. The international community must be consistent in their support of the law."
"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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The ICC wants Friday's UN meeting, chaired by Ban Ki-moon, the UN secretary general, and Alpha Oumar Konare, the African Union chairman, to be used to push the Sudanese government to arrest Harun.
But bringing to justice those most responsible for killing over 200,000 people and uprooting more than 2.5 million during the four and a half-year conflict is not on the agenda for the meeting.
Instead, ministers from 26 countries have been invited to discuss international support for new negotiations with Khartoum, the deployment of a 26,000-strong AU-UN force in Darfur and the expansion of humanitarian assistance.
"World leaders have to understand that if the justice component process is ignored, crimes will continue and affect the humanitarian and security operations in Darfur," Moreno-Ocampo said.
Postponing Harun's arrest, he said, would mean "there will be no solution in Darfur" but Moreno-Ocampo also expressed hope that the UN secretary-general's talks with Omar al-Bashir, the Sudanese president, earlier this month might "bear fruit".
'Justice and peace'
At a news conference on Tuesday Ban refused to disclose the details of his discussions with al-Bashir, but said "you should know that I am fully committed to justice and peace".
Asked how al-Bashir responded when asked to hand over Harun and Ali Kushayb, a Janjawid leader, for trial by the ICC, Ban said he raised the issue "more than once in a private conversation" and would continue to raise it.
But Abdalmahmood Abdalhaleem Mohamad, Sudan's UN ambassador, said al-Bashir told Ban that "in no way we are going to surrender any of our citizens to be prosecuted abroad".
Mohamed accused Moreno-Ocampo of politicising his office and coming to New York "to destroy the peace process" instead of helping to ensure the success of the political negotiations in Libya scheduled for October 27.
Before those talks, the UN and its allies must persuade Darfur's fragmented groups of fighter to sit down with the Sudanese government, a goal that has proved elusive in the past.
Abdel Wahid Nur, one of the most influential rebel leaders, has already said he will not participate.
The Darfur conflict began in 2003 when ethnic African rebels took up arms against the Arab-dominated central government, accusing it of discrimination.
Sudan is accused of retaliating by unleashing Arab fighters known as Janjawid responsible for much of the violence, an accusation the government denies.