The UN has given a sealed list of 51 people suspected of carrying out atrocities in Sudan's Darfur region to the International Criminal Court.
Boxes of documents have been delivered to the court
Last week, the UN Security Council passed a resolution referring the situation in Darfur to the tribunal.
But Sudan's President Omar al-Bashir says his country will refuse to co-operate with the court in The Hague.
And tens of thousands of people have marched through the Sudanese capital, Khartoum, protesting against the UN.
UN Secretary General Kofi Annan handed the names of the 51 suspects to the ICC's chief prosecutor, Luis Moreno Ocampo, at UN headquarters in New York.
The list, drawn up by the UN commission investigating allegations of killings, torture and rape in Darfur, includes Sudanese government and army officials, as well as militia and rebel leaders.
Radio stations and newspapers urged people to join the protest
Earlier on Tuesday, the UN handed other documents outlining the war crimes allegations to the court in The Hague.
Mr Ocampo, said the court would work to end the impunity in Sudan and stop the atrocities.
Sudan is refusing to hand over any of its citizens, preferring to rely on local justice.
Mr al-Bashir swore "thrice in the name of Almighty Allah that I shall never hand any Sudanese national to a foreign court", he is quoted as saying by AFP news agency.
Tens of thousands of people have marched through the Sudanese capital, Khartoum, to protest at the UN's decision to refer the suspects to the ICC.
Newspapers, radio stations and even text messages were used to call on all Sudanese people to take part in the government-backed demonstration, says the BBC's Jonah Fisher in Khartoum.
Protesters gathered outside a key UN building in Khartoum, as well as the French and US embassies, waving banners criticising the UN, the US and its allies, our correspondent said.
"We are coming here to say to America 'no' to these orders. We are not people who have to listen to orders from anybody except the Sudan," one demonstrator said.
The UN Security Council voted to refer the atrocities in Darfur to the ICC last week.
It is the first time a case has been referred to the court in The Hague by the Security Council.
The commission found that Sudanese government forces and militias committed gross human rights violations that could amount to crimes against humanity.
The Sudanese government described the Security Council plan to try criminals in The Hague as "unfair, ill-advised and narrow-minded".
But Darfur's two main rebel groups welcome it.
The UN says at least 180,000 people have died and more than two million have sought refuge from the violence since the two-year conflict began.
A UK parliamentary investigation concluded that as many as 300,000 could have died.
Many of the deaths and atrocities are blamed on the Arab Janjaweed militia, which the government denies arming.
Meanwhile, Darfur rebels have rejected an Egyptian initiative to hold peace talks.
The New York-based rights group Human Rights Watch (HRW) has accused the Sudanese government of trying to intimidate humanitarian relief agencies by arbitrarily detaining aid workers.
HRW says it has documented the arrest and detention of more than 20 foreign and local aid workers in the past four months.
All the arrests took place in Nyala, the capital of South Darfur, and according to HRW's Peter Takirambudde are "nothing less than a campaign to harass and threaten aid agencies to keep them in line".