Appeals judges at the International Criminal Court upheld on Tuesday the conviction of former Congolese militia leader Bosco Ntaganda for war crimes and crimes against humanity, and confirmed his 30-year jail sentence.

"Having rejected mister Ntaganda's grounds of appeal in their entirety, the appeals chamber hereby confirms the trial chamber's sentencing judgment," presiding judge Howard Morrison said.

Ntaganda's lawyers had sought to overturn his conviction, saying the original trial was riddled with legal errors.

But the appeals judges dismissed all of the almost 30 grounds of appeal raised against his conviction and sentence, the longest the court has handed down.

Ntaganda was sentenced in 2019 for murder, rape, using child soldiers and other atrocities committed when he was military chief of the Union of Congolese Patriots (UPC) militia in eastern Democratic Republic of Congo in 2002-2003.

During the conflict, Ntaganda’s UPC, dominated by the Hema clan, targeted rival Lendu people for expulsion from the mineral-rich Ituri region.

Hundreds of civilians were killed and many thousands were forced to flee in the sprawling central African country of about 90-million where many live in extreme poverty.

The ICC is an international court set up in 2002 to prosecute war crimes and crimes against humanity when member states are unable or unwilling to do so.

In March, judges at the ICC ordered reparations of $30-million for Ntaganda's victims.