At least 51 people have been murdered by an Islamist-linked militia in the Congo in a brutal massacre where militants hacked apart civilians with machetes.

The army says the attack was carried out by the Allied Democratic Forces, a Islamist group originating from Uganda which merged with other disparate militias. The group has carried out an insurgency against the Ugandan and the Congolese governments since 1996.

The group is based in the Democratic Republic of Congo’s North Kivu province and is reported to have links with the Somalian Islamist terrorist group Al-Shabaab.

The killings took place on Saturday night in the town of Beni. Government estimates initially put the death toll at 36, but on Sunday local mayor Edmond Masumbuko put the toll at 42.

NGOs have counted more casualties. “Our team on the ground has counted 51 bodies slain with machetes,” said Teddy Kataliko, a member of a local NGO alliance.

He told AFP that civilians were angry with the government for failing to protect their family members. “They decided to hold private funerals and refused to allow the government to bury them, because it could not guarantee their security while they were still alive,” he said.

In 2014, the Congolese army launched an offensive against the ADF bases in North Kivu province and have since driven them from many of their former strongholds.

In 2015, the leader of the ADF, Jamil Mukulu, was arrested in Tanzania and extradited to Uganda.