After touring a former slave house and paying homage to the humans who were sold there, President Bush (searchis visiting the place where the apartheid system of white-minority rule further oppressed black Africans through the 20th century.

With a decision pending on whether he will send U.S. troops to help enforce peace in Liberia, Bush planned meetings Wednesday with South African President Thabo Mbeki (searchin Pretoria (search).

The two men were expected to discuss AIDS (search), the campaign against terror, trade, and the political and economic crisis unfolding in neighboring Zimbabwe.

But rising anti-American sentiment fed by unhappiness over Bush's decision to wage war in Iraq was casting a shadow over his visit to South Africa on the second day of a five-day, five-nation tour of sub-Saharan Africa.

Dozens of South Africans protested this week outside the U.S. Embassy here and the consulates in Johannesburg and Cape Town. Protests by political parties, trade unions and other groups were planned during Bush's stay in southern Africa, which ends Friday.

Besides resentment over the war, South Africa's generally positive relations with the United States were dealt a blow by the Bush administration's decision to end military aid to 35 countries, including South Africa, that opposed the U.S. demand for immunity for Americans in the International Criminal Court.

Continued tensions in Liberia also vied for Bush's attention. On Tuesday, Bush told reporters that he had promised U.S. participation to help enforce a temporary cease-fire and to allow for a peaceful transition of power in that West African country.

"We're now in the process of determining what that means," he said when asked if such participation meant U.S. troops.

Aides suggested his comments signaled there would be some involvement of U.S. forces -- although the size and role of such a unit remained undetermined.

Bush has said that Liberian President Charles Taylor must step down. Taylor has accepted an offer of asylum in Nigeria, but told The Associated Press in an interview that he would only leave after a peacekeeping force is sent in to maintain order.

Bush's visit to Africa began Tuesday in the Atlantic port city of Dakar, the capital of Senegal. He met privately with Senegalese President Abdoulaye Wade, then with a larger group that included Wade and the heads of seven other West African democracies.

Bush and his party then rode in Wade's presidential yacht to Goree Island for a tour of a centuries-old slave house where hundreds of thousands of Africans were bought and sold like cargo.

In a speech on the island, Bush stopped short of issuing the blanket apology for slavery that some civil rights advocates had sought. But he acknowledged that the scars of slavery still sting American society.

"But however long the journey, our destination is set: liberty and justice for all," the president said.

Bush wants African leaders to put more pressure on Zimbabwe President Robert Mugabe to restore democracy by stepping down and holding new elections. Mbeki has insisted that he will not pressure Mugabe.

About half of Zimbabwe's population faces starvation. Dozens have been killed in state-orchestrated political violence. Thousands more have been beaten, jailed, raped or tortured for their views.

On the AIDS front, South Africa has the highest number of infections on the continent -- 5 million. It also is one of 14 hardest-hit African and Caribbean countries that would benefit under Bush's proposed five-year, $15 billion AIDS initiative.

Mbeki's government has been criticized as being lackadaisical in its efforts to fight the disease, and Mbeki himself has said he does not believe the human immunodeficiency virus causes AIDS.

Absent from Bush's schedule is any appearance or meeting with Nelson Mandela, who preceded Mbeki as South Africa's president.

Mandela, the worldly popular leader and hero of the anti-apartheid movement, has been a harsh and outspoken critic of Bush for leading the war against Iraq without support from the United Nations.

Administration officials have said Bush's time was being reserved for current African heads of state. Mandela was expected to be out of the country for the Bush visit.

Bush is touring Africa to promote his economic development and AIDS initiatives and to increase cooperation in stopping the spread of terrorism.

He was traveling with first lady Laura Bush and daughter Barbara, and planned stops Thursday in Botswana, Friday in Uganda and Saturday in Nigeria -- all important U.S. allies in the war on terrorism.