New York - The UN Secretary General Ban Ki-moon on Wednesday urged Burundi to reverse its decision to break ties with the UN rights office following a report warning of a risk of genocide.The United Nations also reminded Bujumbura that it must still co-operate with ongoing investigations of the International Criminal Court (ICC) despite its decision to pull out of the treaty setting up the world court."We are very disappointed to learn of the government's decision to cease co-operation with the office of the high commissioner for human rights," the UN spokesperson Stephane Dujarric told reporters.The office with its 51 staffers will remain open in Burundi "pending further discussion", said Dujarric."The secretary general calls on the government of Burundi to continue its co-operation with the high commissioner" for human rights, he added.Burundi on Tuesday suspended co-operation with the rights office, accusing it of helping to draft a "dishonest" report that blamed the government for a surge in violence in the country.War crimes The government a day earlier barred three UN rights experts who wrote the report from entering the territory.The report documenting cases of torture and killings paved the way for the creation of a formal Commission of Inquiry to gather evidence of atrocities.Burundi's parliament on Wednesday voted to withdraw from the Rome treaty setting up the ICC.The United Nations said it had yet to be formally notified by Burundi of its withdrawal, but added that if Bujumbura goes through with the decision it would be "regrettable."Dujarric said that under the Rome statutes, the decision to pull out of the treaty will become effective one year after Bujumbura has formally notified the United Nations of its decision."State-parties that decide to withdraw are still obliged to co-operate with any criminal investigations or proceedings that were commenced before the effective date of withdrawal," said the spokesperson.The ICC opened its investigation of possible war crimes in Burundi in April.The UN Security Council is due to hold a closed-door meeting on Burundi on Thursday.The political crisis began in April 2015 when President Pierre Nkurunziza announced plans to run for a controversial third term in power, which he went on to win.Violence since then has killed more than 500 people and driven 300,000 people across the border to seek refuge in neighboring countries, according to the United Nations.