Mr. al-Bashir became the first sitting head of State to be indicted by the Court, which charged him with two counts of war crimes and five counts of crimes against humanity last March.

But the chamber at that time rejected Prosecutor Luis Moreno-Ocampo's application to charge the Sudanese leader with genocide, ruling that there was insufficient evidence.

The ICC's appeals chamber today found the standard of proof set by the pre-trial chamber to be too demanding at the arrest warrant stage, amounting to an “error of law,” according to a news release issued by the court, which is based in The Hague. The pre-trial chamber has been directed to decide anew whether or not Mr. al-Bashir should be charged with genocide.

The United Nations estimates that an estimated 300,000 people have been killed and another 2.7 million forced from their homes since fighting erupted in 2003 in Darfur, pitting rebels against Government forces and allied Janjaweed militiamen.

In December, the ICC Prosecutor told the Security Council that indiscriminate bombings, rape and other crimes are continuing in Darfur, with the Government of Sudan still refusing to cooperate with his office and its indicted President and other suspects remaining at large.

Soon after the arrest warrant for Mr. al-Bashir was issued, authorities expelled 13 international non-governmental organizations (NGOs) and revoked the permits of three local groups, dealing a blow to humanitarian efforts in the region.

“The decisions to expel humanitarian workers and silence others by threats of expulsion, or the attempts at restricting the freedom of movement of UNAMID [joint UN-African Union peacekeeping force in Darfur] are part and parcel of this policy to reduce the monitoring capacity of the international community,” Mr. Moreno-Ocampo said.#