A South African private military firm will hire outside lawyers to look into its activities in Mozambique, it said, after Amnesty International accused it of firing indiscriminately on civilians while helping the government fight an insurgency.

In a report issued on Tuesday, Amnesty accused both the government and the insurgents of war crimes against civilians, including killings, dismemberment, torture and abductions.

More than half a million people have been displaced and hundreds killed in Mozambique's Cabo Delgado region since Islamist militants launched an insurgency in 2017.

The government has hired South African private military firm Dyck Advisory Group to help it fight the Ahlu Sunnah Wa-Jama insurgents, known locally as Al-Shabaab, who have declared their allegiance to Islamic State.

Mozambique has previously denied accusations that its soldiers had committed atrocities, saying killings blamed on government forces were carried out by Islamist insurgents impersonating troops.

Mozambique's Ministry of Interior General Command did not respond to phone and emailed request for comment from Reuters on the Amnesty report. An official told Reuters on condition of anonymity that the government would respond to the allegations later.

Reuters was not able to contact the militants.

WHAT I SAW IS DEATH

In its report, titled 'What I Saw Is Death': War Crimes in Mozambique's Forgotten Cape', Amnesty said it had interviewed 79 internally displaced people between September and January, and reviewed satellite imagery, photographs, medical records and ballistics information. Reuters was not independently able to verify the material described in the report.

The report accused Dyck Advisory Group staff of opening fire indiscriminately on civilians while pursuing suspected fighters.

Lionel Dyck, the founder of the company, told Reuters: "We take these allegations very seriously and we are going to put an independent legal team in there shortly to do a board of inquiry and look at what we are doing." He declined to give further details of the group's mission in Mozambique.

According to Amnesty, insurgents had abducted young women and children, including young girls. "....Fighters routinely kill civilians, loot their homes, and then burn them down using petrol."

It said residents used separate words to describe two Al-Shabaab methods of killing: "beheaded" and "chopped", the second of which, it quoted a 75-year-old man as saying, meant "being 'divided like a cow.'"

As for the government forces, Amnesty said videos and photos showed "the attempted beheading, torture and other ill-treatment of prisoners, the dismemberment of alleged Al-Shabaab fighters, possible extrajudicial executions, and the transport and discarding of a large number of corpses into apparent mass graves."

In the videos, the security forces were identified by their uniforms and spoke Portuguese and a local language from southern Mozambique, said Amnesty, calling for a thorough investigation.

The United Nations has said the violence and humanitarian crisis in Mozambique will worsen without international help as displaced people faced overcrowding, malnutrition and a lack of essentials including food and water.