Zimbabwe's president has defended his government's campaign of demolitions and evictions which the UN believes has left about 250,000 people homeless.
The opposition say their supporters are being punished
Robert Mugabe said the removal of illegal homes and market stalls was part of a bid to fight crime and clean up cities.
At least three children have been crushed to death during the campaign.
Earlier, the African Union rejected calls from the UK and US to speak out against President Mugabe's government.
An spokesman said the organisation had many more serious problems to consider.
In remarks broadcast on state television, Mr Mugabe said: "As much as 3 trillion [Zimbabwe dollars - about $3bn] has been committed to this programme... There is a clear construction and reconstruction programme.
"We pledged to revitalise our cities and towns and to deliver as many as 1.2 million housing units and residential stands by the year 2008. We also undertook to reorganise our SMEs [small and medium business enterprises] so they could grow and expand in an environment that is supportive, clean and decent."
Zimbabwe's Local Government Minister, Ignatius Chombo, said he was happy with what he described as a normal clean-up operation.
Speaking to the BBC, he denied that it had created widespread humanitarian problems, and said the demolitions had been welcomed by all patriotic Zimbabweans.
The opposition says the demolitions - codenamed Operation Restore Order - are meant to punish urban residents, who have rejected President Mugabe in recent elections.
Urging the AU to take action, US Secretary of State Condoleezza Rice described recent events as "tragic".
But AU spokesman Desmond Orjiako told the BBC's Network Africa programme: "If the government that they elected say they are restoring order by their actions, I don't think it would be proper for us to go interfering in their internal legislation."
His comments were backed up by South Africa, Zimbabwe's giant neighbour, which some see as the key to solving Zimbabwe's problems.
Presidential spokesman Bheki Khumalo said he was "irritated" by calls from UK Foreign Secretary Jack Straw to do more to end the "horrors" in Zimbabwe.
"South Africa refuses to accept the notion that because suddenly we're going to a G8 summit, we must be reminded that we must look good and appease the G8 leaders," he said.
"We will do things because we believe they are correct and right."
The G8 summit of the world's most powerful nations is due to discuss efforts to relieve poverty in Africa on 8 July in Scotland.
Many African leaders see Mr Mugabe as a hero for leading the fight against colonial rule.
South Africa's President Thabo Mbeki has questioned why the West is so concerned by Zimbabwe but makes relatively little noise about other African emergencies, such as the Democratic Republic of Congo, where some three million people died in a civil war, and where armed bands kill, rape and loot with impunity in some areas.
The BBC's Elizabeth Blunt also says that many African countries have carried out similar slum clearances and so will be unwilling to criticise Zimbabwe.
Some 46,000 people have been arrested for trading without a licence, hoarding and illegal possession of foreign currency, Zimbabwe's police chief Augustine Chihuri said.
Mr Chihuri said that burglary and car-theft had declined by 20% since the operation began four weeks ago.
The children who have died were crushed to death when their homes were knocked down during Operation Murambatsvina [Drive out rubbish].
Some children have left school after their homes were demolished
The police have moved across Zimbabwe's urban areas, armed with bulldozers and sledge-hammers, destroying shacks and informal markets.
Often, residents have been made to demolish the structures themselves.
The UN is due to send a special envoy to Zimbabwe to investigate the demolitions.
Many people are living on the streets, while others have returned to their rural homes, encouraged by the government.