"The chamber is not satisfied that there are substantial grounds to believe that Mr Abu Garda can be held criminally responsible as either a direct or indirect co-perpetrator," the court said in a statement.

Abu Garda who was a top member of the Justice and Equality Movement (Jem), the main rebel group in Darfur, is the first Sudanese rebel leader to appear before the court in The Hague.

Abu Garda who left Jem in 2008 and formed the United Resistance Front was one of three Sudanese rebels wanted in link with the attack and appeared before the ICC in The Hague last May to face the charges.

The international Criminal Court has already issued a warrant for president al-Bashir’s arrest in March and accused him of war crimes in the western Sudan region of Darfur. Bashir denies the charges.

ICC accuses Bashir of running a campaign of rape, murder and other crimes against humanity in Darfur.

The U.N. says the ongoing conflicts in Darfur has killed some 300,000 people and displaced more than 2.5 million other.

The conflict in Darfur has been going on since 2003 when black African rebels began to take arms against the Sudan government.