Congolese state security services shot, burned, beat and hacked to death at least 48 civilians and reportedly hired thugs to attack protests last month against the extension of President Joseph Kabila's mandate, the United Nations said on Friday.



The death toll of the two days of violence in the capital Kinshasa, which also included four police officers killed by protesters and one other civilian, was higher than during the 2011 electoral process, the U.N. Joint Human Rights Office in Congo (UNJHRO) said in a report.



Democratic Republic of Congo's government spokesman and justice minister could not be immediately reached for comment and a police spokesman said he had not yet seen the report.



The government denied last week that on-duty security forces opened fire on protesters, who authorities say were conducting an armed insurrection. In its own report, it said 32 people, including three police officers, were killed by protesters or private security guards, or in accidents.



Congo's main opposition alliance had called for a march on Sept. 19 to demand that Kabila, who has ruled the vast central African country since 2001, step down in December as required by constitutional term limits.



The country's ruling coalition and other smaller parties agreed last week to postpone elections planned for November until April 2018, citing logistical problems registering millions of voters, but most major opposition parties have rejected the accord.



Congo has never experienced a peaceful transition of power and international donors fear that the impasse over Kabila's plans to stay on will lead to widespread bloodletting.



In total, UNJHRO said, there were at least 422 victims of human rights abuses by state agents in Kinshasa between September 19 and 21.



"This is clearly outrageous and serves to fuel an already explosive situation in the country," said U.N. High Commissioner for Human Rights Zeid Ra'ad Al Hussein.



Of the civilians killed, 38 were shot by the police, army and presidential guard and seven were burned to death by members of the presidential guard, including during an attack on the headquarters of the main opposition party, the report said.



Four police officers were burned alive or beaten to death by protesters who also looted the headquarters of ruling coalition political parties, UNJHRO said.



The death toll could be much higher due to the authorities' restrictions on access to morgues and other facilities, it said.



The report said UNJHRO had received "concordant reports about the distribution by the authorities of machetes and money to about a hundred young men, with a view to disturbing the demonstration."



The International Criminal Court's chief prosecutor sent a delegation to Congo this week to urge restraint by all parties in the coming months and warned that human rights abuses could be prosecuted by the court.