"It is a profoundly distressing report, which confirms that Operation Murambatsvina [Drive Out Trash/Restore Order] has done a catastrophic injustice to as many as 700,000 of Zimbabwe's poorest citizens, through indiscriminate actions, carried out with disquieting indifference to human suffering," Kofi Annan said after receiving the report which he commissioned. It was written by a respected Tanzanian diplomat, Anna Kajumulo Tibaijuka, executive director of UN Habitat based in Nairobi.
"I call on the government to stop these forced evictions and demolitions immediately, and to ensure that those who orchestrated this ill-advised policy are held fully accountable for their actions," Mr Annan said.
The reportsays that at least 2.4 million people have been affected to some degree by the operation described as an "indiscriminate and unjustified" violation of international law. It had made 700,000 people either homeless or jobless.
Ms Tibaijuka arrived in New York yesterday to present the report to Mr Annan after a three-week investigation in Zimbabwe. It remained uncertain whether it would be taken up by the Security Council.
But the Foreign Secretary, Jack Straw, said: "We will be speaking to our international partners, in Africa, in the European Union, and at the United Nations, to ensure that the international community responds swiftly, appropriately and constructively."
President Mugabe claimed the operation, which began without warning on 19 May, was aimed at cleaning up "trash" from urban areas, ridding towns of criminal activities and restoring their "reputation of cleanliness".
But the UN envoy said: "While purporting to target illegal dwellings and structures and to clamp down on alleged illicit activities, [the operation] was carried out in an indiscriminate and unjustified manner, with indifference to human suffering.Even if motivated by a desire to ensure a semblance of order in the chaotic manifestations of rapid urbanisation and rising poverty characteristic of African cities, none the less Operation Restore Order turned out to be a disastrous venture."
Officials in Zimbabwe's foreign ministry who have seen the report said it had sent tremors through the regime because it was written by an organisation that had hitherto supported Zimbabwe. The Foreign Minister, Simbarashe Mumbengegwi, said that the report's claim that the demolitions violated international law was "definitely false".
"The report described the operation in vastly judgemental language which clearly demonstrates its inbuilt bias against the operation," he said.
A senior Zimbabwean foreign ministry official, speaking on condition of anonymity, said: "We did not expect a favourable report but we equally had not anticipated such harsh condemnation."
The report, written in harsh language uncharacteristic of the UN, suggests that the demolitions campaign might qualify as a crime against humanity in international law and calls for the prosecution of those responsible. It warns that Zimbabwe will take years to recover from the "crash operation " conducted using a set of colonial-era laws and policies "that were used as a tool of segregation and social exclusion".
African nations on the Security Council, supported by Russia and China, have prevented the issue of Zimbabwe reaching its official agenda. Other members are pushing to invite Ms Tibaijuka to address the council on her report as early as next week, however.
Zimbabwe's opposition says the operation was aimed at its supporters in its urban strongholds, to drive them into rural areas where they would be overwhelmed by Mr Mugabe's violent youth militias.
The claim gained credence when the Home Affairs Minister, Kembo Mohadi, said that those affected should go into the rural areas. Critics compared it to Pol Pot's policy in Cambodia in the 1970s of driving urban people into rural areas for "political re-education".
The clean-up policy is controversial within the ruling party, however. A Zanu-PF central committee member, Pearson Mbalekwa, resigned over the campaign early this month.
On Wednesday police raided several churches in Zimbabwe's second-largest city, Bulawayo, and rounded up scores of displaced people who had been sheltering in church halls. South African and Zimbabwean church leaders trying to help the poor in the city were detained overnight.
The Zimbabwe government brushed off a UN timetable for it to respond within 48 hours. Zimbabwe's UN ambassador, Boniface Chidyausiku, said his country was not facing an inquisition and would not accept any such timetable. He blamed problems in Zimbabwe on travel sanctions imposed by the European Union and the US. But critics blame Mr Mugabe's mismanagement and skewed priorities for Zimbabwe's economic collapse.
The UN report will make it increasingly difficult for Mr Mugabe's African allies to continue supporting him.