An Appeals Chamber of the International Criminal Court has again opened the prospect of charging Sudan's President Omar al-Bashir with genocide over killings in Darfur.

In a ruling issued on Wednesday, the chamber ordered a court pre-trial panel which last year issued a warrant for Bashir's arrest on charges of war crimes and crimes against humanity to reconsider the issue of adding the crime of genocide to the arrest warrant.

When the panel issued the warrant last March, two of three judges said the prosecutor, Luis Moreno-Ocampo, had failed to provide reasonable grounds for believing that Bashir had the "specific intent" to destroy the Fur, Masalit and Zaghawa ethnic groups in Darfur. As a result, they refused to include genocide as one of the charges.

But the Appeals Chamber said Wednesday that the standard of proof the panel had adopted was "too demanding at the arrest warrant stage." It emphasised it was deciding a question of procedural law, not the question of whether Bashir was, or was not, responsible for genocide.

The chamber rejected the prosecutor's request that it make a finding itself that there were reasonable grounds to believe that Bashir acted "with genocidal intent." It instead directed the pre-trial panel to make that decision.

At present Bashir stands accused on seven counts, five of crimes against humanity - including murder, extermination, forcible transfer, torture and rape - and two of war crimes - intentionally directing attacks and civilians, and pillaging.

Bashir is suspected of being responsible for attacks in which forces backed by the Sudanese government were guilty of "murdering, exterminating, raping, torturing and forcibly transferring large numbers of civilians, and pillaging their property."

Sudan refuses to hand Bashir over to the court for trial. The African Union said last year it would not enforce the arrest warrant, although some African governments have said they would act upon it if Bashir entered their territory.