Johannesburg - US Secretary of State Hillary Rodham Clinton on Friday called for renewed efforts from South Africa to ensure Zimbabwean President Robert Mugabe holds up his end of a fragile power-sharing agreement.

Clinton, who is on the second leg of a seven-nation African tour that began Tuesday in Kenya, was addressing the business community in Johannesburg after meeting earlier with her foreign affairs counterpart Maite Nkoana-Mashabane and former president Nelson Mandela.

US President Barack Obama took "very personally" the suffering of the people of Zimbabwe, of which South Africa was also keenly aware, as home to between 3 and 4 million Zimbabwean refugees, she said.

"This (Zimbabwe's political turmoil) is a cost to you (South Africa), " she said.

"It's a problem that time will eventually take care of, but how long?," she asked rhetorically, apparently referring to 85-year-old Mugabe in remarks that drew laughter.

"There needs to be renewed effort to make sure the reform agenda is followed up on (in Zimbabwe)," said Clinton, who is scheduled to press the point in a meeting Saturday with President Jacob Zuma.

Earlier this week Zuma pledged to intercede with Mugabe on issues barring progress in the country's six-month-old coalition government.

The former opposition Movement for Democratic Change says the peace deal is being undermined by Mugabe's refusal to recall his cronies from key posts as well as by a renewed campaign of arrests of MDC MPs.

Clinton said she had been "delighted" to meet Madiba again at his foundation, referring to anti-apartheid icon Mandela by his clan name.

She also visited a health clinic near Pretoria where the US government is funding care for HIV/AIDS patients.

Clinton's visit to South Africa is aimed a kickstarting a new era in US-South African relations, which were strong during the presidencies of Mandela and her husband Bill Clinton but flagged under former presidents George Bush and Thabo Mbeki.

Clinton assured Africa was high up on Obama's foreign policy agenda and that the US saw South Africa, Africa's biggest economy, as having a leadership role in Africa and beyond.

She and Nkoana-Mashabane announced the creation of a new forum to govern US-South African relations.

The US would also be looking at how to allow more South African products enter the US market duty-free, said Clinton, who praised South Africa's prudent economic management, which is credited with shielding the country from the worst of the global financial crisis.

"Frankly we (the US) could learn a lot from your example," she said.

After visiting South Africa, Clinton will continue her tour in Angola, the Democratic Republic of Congo, Nigeria, Liberia and Cape Verde.(dpa)