Burundi said Tuesday it will suspend all cooperation with the UN rights body, while barring entry to three UN investigators who had accused the government of gross human rights violations.
Government spokesman Philippe Nzobonariba accused the Office of the UN High Commissioner for Human Rights of "complicity" with the three experts, who published the results of their investigation in a UN report.
A letter signed by Foreign Minister Alain Aime Nyamitwe said Pablo de Greiff of Colombia, Christof Heyns of South Africa and Maya Sahli-Fadel of Algeria had been declared persona non grata.
The three independent experts had been mandated by the UN Human Rights Council in December to investigate the situation in Burundi.
The UN said that the work of its more than 50 human rights officers in Burundi was "critical," according to Stephane Dujarric, spokesman for UN Secretary General Ban Ki-moon, noting that he was not aware of the letter suspending all cooperation.
"We feel their work is critical in order to shine light on the situation the country - and we very much hope that they will be able to continue their work," Dujarric said.
The East African country has been in turmoil since President Pierre Nkurunziza announced his intention to seek a controversial third term in office in April 2015, and won an election the following July. Hundreds have been killed in the ensuing political violence.
The three experts visited the country and informed the UN of their findings in September, accusing the authorities of killing and torturing opponents.
Nzobonariba described the findings as "biased" and accused the three of trying to destabilize the country.
They were declared persona non grata just days after Burundi announced its intention to pull out of the International Criminal Court, where prosecutors intend to investigate the violence in the country.