Presidential elections scheduled to take place in Burundi next week are likely to cause "major instability and confrontations” that may spread across the region, the United Nations human-rights agency warned.

The UN Security Council should take immediate action to prevent the country from sliding back into violent conflict, the agency said in a statement e-mailed from Geneva on Thursday.

"The world is witnessing an escalating pattern of politically motivated violence in Burundi,” the UN’s special rapporteurs said. "The international community must not simply stand by and wait for mass atrocities to unfold, thereby risking a major conflict of regional proportions before it finally decides to act.”

Burundi, a landlocked coffee-producing nation, has been roiled by unrest since late April’s announcement that President Pierre Nkurunziza will run for re-election, a decision that opponents say violates a two-term limit stipulated in a 2005 peace accord that ended a 12-year civil war. The decision triggered a failed coup attempt and protests that have left at least 77 people dead and have forced at least 145,000 others to take refuge in neighboring countries.

The violence has raised fears of a return to conflict if rebel groups abandon peace deals that ended the war in which 300,000 people died. It also has the potential to destabilize the Great Lakes region, which includes Congo, Africa’s biggest copper and tin producer, and Rwanda, where a genocide took place in 1994.

Suspected rebels

Earlier this week, Burundi’s army said it killed 31 suspected rebels and detained another 170 in the country’s north. Frederic Bamvuginyumvira, an opposition leader, said July 14 that at least 45 people have been killed across the nation in the previous week, some of them activists opposed to Nkurunziza’s re-election bid.

"If the government persists in holding presidential elections under the current circumstances – something even the former first Vice President objected to after also having fled the country – they will in no way confer any legitimacy on the to-be-elected authorities,” the UN experts warned.

The presidential vote is scheduled for July 21.