The U.N. officers, who did not want to be identified, told Reuters that Sudanese officials had ordered a crackdown on aid groups they suspected of supplying evidence to the International Criminal Court for a war crimes case against President Omer Al Bashir.

But the head of the Humanitarian Aid Commission in the region denied the accusations, saying his office was doing all it could to assist development groups.

The Under-Secretary of Foreign Affairs Ministry Mutrif Siddiq rejected these statements.

Meanwhile, the government did not deny occurrence of violations by security and intelligence organs as stated in a recent report by the UN High Commissioner for Human Rights (UNHCHR).

The report said intelligence and security organs, police, Sudan Armed Forces and Sudan People's Liberation Army have all committed violations of Sudanese and international law, in the form of arbitrary arrests of civilians, in the length and manner of their detention, and in the physical treatment of detainees.