The International Criminal Court said on Thursday it will start its first trial -- that of a Congolese militia leader accused of sending child soldiers to fight -- on June 23.

The trial of Thomas Lubanga at the world's first permanent war crimes court had been due to start on March 31, but was delayed after defence lawyers said prosecutors had not disclosed all the evidence as stipulated by the court.

Lubanga, who founded and led a militia in Congo's eastern Ituri district, was arrested in 2006 and is accused of enlisting and conscripting children under the age of 15 from 2002 to 2003.

He has denied the charges.

The ICC was set up in 2002 and is now backed by 105 nations. It is also investigating war crimes in Uganda, Sudan's Darfur region and the Central African Republic, but it has only three suspects in custody so far, all from Congo.

Lubanga led the Union of Congolese Patriots (UPC), a militia now registered as a political party, and is accused of using children to kill his enemies in an ethnic conflict in Ituri between the Hema and Lendu, and in clashes between groups vying for control of mines and tax revenues.

Experts estimate that a decade of violence in Congo has killed 5.4 million people, mainly through hunger and disease.

The court said on Wednesday it had decided not to hold part of the trial in the Democratic Republic of Congo after Kinshasa said it was concerned it could fuel ethnic tension.

The court will hold a hearing to confirm charges against its two other suspects in custody, allied Congolese militia leaders Germain Katanga and Mathieu Ngudjolo, on May 21.

Katanga and Ngudjolo are both being prosecuted for crimes including murder, sexual slavery and using child soldiers that are alleged to have been committed during and after a joint attack by their forces on the village of Bogoro in 2003.