A United Nations Human rights report has revealed a mass grave of migrants from Africa on Libya- Tunisia border.

The High Commissioner for Human Rights, U.N Volker Türkon on Tuesday said his office was following up on reports of a mass grave in the desert along the Libya-Tunisia border, after the bodies of at least 65 migrants were found at another site this year.

He denounced widespread violation of migrants and refugees in Libya, who travel through the Sahara Desert and across the southern Mediterranean.

Turkon said abuses against migrants were being “perpetrated at scale, with impunity” by both state and non-state actors. Listing crimes including human trafficking, torture, forced labour, extortion, starvation, detention and mass expulsions.

“I urge the authorities to respond swiftly to our inquiries, and to investigate these crimes fully,” he told the U.N. Human Rights Council in Geneva in a speech addressing Libya’s record over the last year, where he noted “disturbing developments.

Meanwhile, Libya’s Justice Minister Halima Ibrahim Abdulrahman stressed her country’s commitment to human rights and did not respond directly to Turk’s comments on the mass graves.

“Libya gives special importance to the rights of refugees,” she told the council, adding that some of Turk’s points were “not in line with reality”.

Libya and Tunisia are vital partners in the European Union’s efforts to stem the flow of migrants across the Mediterranean from North Africa into southern Europe.

A U.N. fact-finding mission on Libya has previously found grounds to believe crimes against humanity such as torture have been committed against migrants.

In March, the UN international of migration reported that 65 bodies of migrants were discovered at the mass grave site in southwest Libya’s Al-Jahriya valley.