The president of the Democratic Republic of Congo, Joseph Kabila, announced an amnesty on Wednesday for former members of the defeated M23 rebel army.

The amnesty covers "acts of insurgency, acts of war and political offences" committed in the DR Congo up to December 20, 2013, when the bill was approved by the government.

Announced on state television on Wednesday, the presidential order was welcomed by the UN and Western countries as a way of moving on from the conflict, which ended with an ignominious defeat for the M23 rebels in early November.

More serious crimes are excluded from the amnesty, including genocide, crimes against humanity, terrorism, torture, sexual violence, child conscription and embezzlement and looting.

But that did not prevent heavy criticism from local human rights activists. The amnesty "trivialised serious crimes and human rights violations," said the National Network of NGOs on Human Rights in the DRC (Rhenadoc).

The announcement of the amnesty coincided with the arrival Wednesday of Mary Robinson, UN special envoy for the Great Lakes region.

She was in Kinshasa on the first stop of an eight-day tour of the region, aimed at pushing forward a peace agreement signed by 11 African countries in February 2013.

Under the agreement, they vowed not to support rebel movements in neighbouring countries.

The UN and Kinshasa have accused both Rwanda and Uganda of actively backing the M23 during the conflict that began in April 2012 following a mutiny by former rebels that had joined the Congolese army.

The amnesty law is seen as key to encouraging the return of former rebels who fled across the border in the wake of their defeat at the hands of the national army and a special UN intervention force.

Close to 1,300 former rebels, who once made up the strongest army in the mineral-rich but impoverished Kivu region, have been left in limbo in a camp in Uganda since the end of the fighting.

Former rebels will now have six months to approach the government and vow "in writing, on their honour, not to commit any acts that come under the present amnesty".

The law will not safeguard the former rebels from civil lawsuits brought by victims of the conflict.

In a joint statement by representatives of the UN, EU, US and African Union, the amnesty was welcomed as "a positive signal" and a "historic achievement".