Anna Tibaijuka, executive director of housing agency UN-HABITAT, has been in Zimbabwe since Sunday on a mission to assess the crackdown which Mugabe's critics have condemned as a serious human-rights violation.
After meeting the president on Wednesday, Tibaijuka toured Harare's oldest township of Mbare, where thousands of illegal shops and homes have been flattened in an operation locals have dubbed "the tsunami."
"We had very good discussions, constructive discussion," she said after one and a half hours of talks with Mugabe. She offered no further details.
Western countries and organisations including Britain, the US, the Commonwealth and the European Union have criticised the operation, which has caused the deaths of at least two children crushed in demolished houses.
Mugabe's government has defended the demolitions, known as Operation Restore Order, saying they were meant to root out black market trade in scarce foreign currency and basic food commodities which had thrived in shantytowns.
The veteran leader said he told UN Secretary-General Kofi Annan's envoy his government wanted to implement the clean-up before 31 March parliamentary polls but had feared it would be misconstrued as an attempt to drive out opposition supporters.
Zimbabwe children stand next to
their destroyed family home
"We had wanted to do this before the elections but then we feared it would be said that we were preparing the way for our own victory and affecting the position of the MDC adversely.
Mugabe, whose government is at odds with former colonial power Britain mainly over its land reforms, took another swipe at British Prime Minister Tony Blair, suggesting he had tried to influence Tibaijuka's mission.
"She is a United Nations director of Habitat and belongs to the United Nations and not to stupid Blair," the 81-year-old leader said. Tibaijuka said she would report only to Annan.
Mugabe said he believed the demolitions would bring long-term benefit, despite criticism in the British media. "Obviously there is some degree of suffering even when you break down a slum, but as I told (Tibaijuka), yes there is discomfort now, but discomfort in order to get comfort later."
Tibaijuka later toured Harare's teeming township of Mbare, among areas worst hit by the crackdown, in advance of similar visits in other cities.
"We are suffering out in the cold during the nights, please help us get places to stay," one man shouted in the local Shona language as the envoy's team walked along rubble-strewn streets.
This week Mugabe's government vowed to step up a new housing programme to benefit those left homeless, which aid agencies have pegged at over 300,000. Zimbabwe's main opposition says the figure is now more than 1.5 million.