Maputo, Sep 15 (IANS): The Mozambique authorities have assured of investigation into a video showing men dressed in army uniforms beating and killing a naked woman in the restive gas-rich Cabo Delgado province.

The Defence Ministry condemned the footage as 'horrifying' and vowed to 'ascertain their authenticity'. Rights groups have also condemned the killing, the BBC reported.

Mozambique has been battling an Islamist militant group in the north for three years. Its army has been accused of human rights abuses as it tries to put down the insurgency. The government denies the accusations.

The two-minute clip of the killing was shared by several rights groups on Monday. In it a group of men wearing army uniforms surround a woman, one hits her on the head and body with a stick several times before others shoot. They can be heard saying in Portuguese "kill her on the side of the road", as per media reports.

The men can also be heard shouting "you're from al-Shabab", according to a global news agency report, referring to the jihadist group that has led a growing insurgency against the government since 2017.

"The FDS (Defence and Security Forces) reiterate that they do not agree with any barbaric act that substantiates the violation of human rights," the Mozambique army said in a statement.

Zenaida Machado, from the New York-based group Human Rights Watch, called for an investigation saying such acts, if committed by soldiers, sowed distrust in the population and strengthened insurgents' narrative.

"It's the worst case of betrayal," she said, adding that frightened people should not run from insurgents only to find themselves in danger from those supposed to keep them safe.

The group - known locally as al-Shabab, or the youth - have an Islamist agenda, but they are building on decades of local frustrations about unemployment, rigged elections, corruption and violence.