The US President Barack Obama has arrived in South Africa as part of his three-country trip to Africa. President Jacob Zuma will receive Mr. Obama for crucial bilateral talks in Pretoria on Saturday.

The visit also takes place just a few months before South Africa celebrates 20 years of freedom. The South African Presidency says it "greatly appreciates the solidarity provided by the Anti-Apartheid Movement in the United States during the struggle for liberation".

The trip has been overshadowed by concerns for Nelson Mandela who remains critically ill. The 94-year-old was rushed to hospital 3 weeks ago with a recurrent lung infection and has since appeared close to death.

This 2011 photo shows US First Lady Michelle Obama with Mandela in Johannesburg

The White House says it is up to the Mandela family to decide if Mr. Obama should see him.

Meanwhile South African President Zuma cancelled a visit to Mozambique yesterday where he was due to attend an economics conference. He made the decision after medics advised him of Mandela's deteriorating condition.

President Obama was in Senegal yesterday on the first stop on his African trip.

He and President Macky Sall of Senegal held a bilateral meeting at the Presidential Palace in Dakar.

Obama visited a former slave house

In the afternoon, the President and his family traveled to Gorée Island, where they toured a former slave house. The house, which was once the last place slaves were held before being sent to North America, is now a museum.