Human rights groups in Congo have denounced parliamentary approval of an amnesty law covering acts of war dating back to 2006.

Lawmakers approved the law late Tuesday, the last day of the session, after more than three weeks of disagreement between majority and opposition lawmakers over how far back the amnesty would go.

Congo signed a peace deal with the M23 rebel movement in December that allowed for a possible amnesty law. The army defeated M23 last November, one year after the group briefly conquered the eastern city of Goma.

On Wednesday the National Network of Congolese Human Rights NGOs rejected the new law, which President Joseph Kabila is expected to sign. The groups say the law "trivializes" grave crimes and perpetuates a pattern of impunity in the conflict-ridden country.