"We're working together to realise the vision of a free, democratic and prosperous Zimbabwe," Clinton told a media briefing with South Africa's International Relations Minister Maite Nkoana-Mashabane.

The pledge signals a shift in tone between Pretoria and Washington with relations uneasy in recent years due to sharp disagreements over Zimbabwe, the fight against AIDS and the Iraq invasion, under former president Thabo Mbeki.

"We're going to be closely consulting as to how best to deal with what is a very difficult situation for South Africa and for the United States, but mostly for the people of Zimbabwe," Clinton told journalists on the second stop of a seven-nation African tour.

The US has been one of long-serving Zimbabwe President Robert Mugabe's fiercest critics, pushing for evidence of reforms under the new unity government with Prime Minister Morgan Tsvangirai.

Both the European Union and the US maintain a travel ban and asset freeze on Mugabe, his wife and inner circle after accusing him of rigging his re-election and alleged human rights abuses by his government.

"We are attempting to target the leaders of Zimbabwe with sanctions that we think might influence their behaviour without hurting the people of Zimbabwe," said Clinton.

The country's former rivals formed a unity government this year which has stemmed a devastating economic crisis, but has been hit by claims of a crackdown on the former opposition and failure to agree on key posts.

Clinton, speaking in Nairobi at the start of a seven-nation African tour, said she would ask South Africa to "use its influence to mitigate against the negative effects of the continuing presidency of President Mugabe".

A tougher stance in the past by South Africa's new President Jacob Zuma has raised hopes for a stronger relationship with the US, and Clinton is due to meet Zuma on Saturday as she criss-crosses South Africa.

The South African leader pledged this week to raise "weighty issues" plaguing the unity government with Mugabe after a briefing with Tsvangirai.

AFP

It's JZ, leave a message... "Hi, this is Zuma. You know what to do. No, no... not the machine gun. Leave a message..."

Finding love in Zululand Susan Pletts ventures into Zululand and discovers that SA's hidden treasures are its people.

Visit our politics page Need the latest political news, features, interviews and profiles? Visit our dedicated page...