THE HAGUE, Netherlands — Appeals judges at the International Criminal Court have ruled that the court has the authority to prosecute a Congolese rebel — whose trial is already underway — for the alleged rape and sexual slavery of child soldiers by members of the armed group they were serving in.

Rebel leader Bosco Ntaganda’s defense team had argued that allowing the charges to go ahead would amount to a “substantial and unjustified extension of the scope of war crimes law,” the court said in a statement Thursday.

Judge Sanji Mmasenono Monageng says that “international humanitarian law does not contain a general rule that categorically excludes members of an armed group from protection against crimes committed by members of the same armed group.”

Ntaganda has pleaded not guilty to 13 charges. His trial continues.