Mugabe's government has conducted a month-long "clean-up" exercise that has seen thousands cast onto the streets after their makeshift residential shacks and informal businesses were demolished. Aid workers say 200,000 have been made homeless.

"We have done everything we can to raise Zimbabwe's international profile and raise the condemnation across the world, with some success," Straw told reporters ahead of a conference on Iraq.

"The problem that we face is a lack of real commitment by all of Africa's leaders to recognise the scale of the horror that is taking place in Zimbabwe."

Straw acknowledged that Britain, as "former colonial master" of Zimbabwe, had a role to play, but noted that "we are also many thousands of miles away".

"Bluntly, unless and until African leaders as a whole recognise what is going on and take action, not only to condemn it but to deal with it, we are likely to be in for many more months of this kind of tyranny until President Mugabe moves aside," he said.

Mugabe says the clean-up is meant to get rid of settlements which he says have become a haven for illegal traders in foreign currency, fuel and scarce food items.

But critics say the exercise, which has hit thousands of unregistered traders, has merely piled pressure on Zimbabweans faced with unemployment of over 70 percent.