LUANDA/GENEVA (Reuters) - The United Nations human rights office on Friday condemned “serious human rights abuses” committed in the mass deportation of 330,000 Congolese from Angola and called on perpetrators to be held to account.

UN High Commissioner for Human Rights, Michelle Bachelet, said in a statement the office had confirmed about six deaths, reportedly at the hands of security forces, in an operation which Angola says is aimed at ending illegal diamond mining in the country.

The statement follows a report by Reuters that found there had been at least eight deaths in the Angolan town of Lucapa, 150 km (95 miles) from the Congolese border. Three of them had reportedly been killed by security forces.

Angola has denied all wrongdoing, dismissing allegations of abuses as “completely false.”

It says it is asserting its sovereign right to ensure national security and protect its natural resources. The world’s fifth largest producer of diamonds wants to reform the sector to increase state revenues for its second most valuable export after oil.

“Our team was able to confirm six cases of people who were killed, allegedly by Angolan security forces,” UN human rights spokeswoman Ravina Shamdasani told reporters in Geneva.

“All of these victims were men and they were all killed by gunshot wounds in the course of the operations of evacuation in Lucapa in the province of Lunda Norte.”

Shamdasani added that there were further allegations of 10 more deaths that they hadn’t been able to fully verify.

The UN human rights office said it was also concerned about abuses on the Congolese side of the border where many returnees are living without proper shelter, food or sanitation.

Returning Congolese have been subjected to extortion and illegal taxation by the defense and security forces in the DRC, it said.

If returnees are not protected, Bachelet said she feared a renewal of the violence that tore through the Kasai area in 2016 and 2017, killing 5,000 people and displacing 1.5 million.